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Henrique Rigatto - One of the best experts on this subject based on the ideXlab platform.

  • Specificity of a placental factor inhibiting Breathing in fetal sheep
    Reproduction Fertility and Development, 1996
    Co-Authors: R. Alvaro, V. De Almeida, May C. Robertson, Don Cates, Virender Rehan, Zia Haider, A. Jansen, Henrique Rigatto
    Abstract:

    We have found previously that the infusion of a placental extract inhibits Breathing induced by 100% O2 plus umbilical cord occlusion in the fetal sheep, suggesting that a placental factor is responsible for the inhibition of fetal Breathing. To test whether this factor is specific to the placenta and whether it also inhibits spontaneous fetal Breathing (occurring in the absence of cord occlusion), we administered extracts from the placenta, muscle and liver of the pregnant ewe, extracts of fetal liver, and Krebs solution to 16 chronically instrumented fetal sheep at 135 +/- 5 days of gestation. Infusions were made during low-voltage electrocortical activity, 5 to 15 min after a switch from high voltage, when Breathing was well established. Within 90 s of the infusion of the placental extract in the carotid artery of the Fetus, Breathing decreased in 79% (33/42) of the experiments and was completely abolished in 71% (30/42) of them (P < 0.0001 compared with the other infusates). No apnoeas were observed with the Krebs solution (0/19) and the maternal muscle (0/20). Extracts of maternal and fetal liver abolished Breathing in only 17% (4/23) and 21% (6/29) of the experiments respectively (NS compared with Krebs solution). There were no significant changes in blood gas tensions, pH, blood pressure and heart rate associated with the infusion of the extracts. The electrocortical activity (ECoG) switched from low to high voltage in 50% of the experiments using placental extract compared with 0% with Krebs solution and maternal muscle, and with 9% and 17% with maternal and fetal liver respectively (P < 0.005). Breathing output (integral of EMGdi x f) during and after the infusions significantly decreased only with the placental extract. These findings indicate the presence of a factor produced by the placenta which inhibits fetal Breathing and may be responsible for the normal inhibition of Breathing observed in fetal life.

  • A placental extract inhibits Breathing induced by umbilical cord occlusion in fetal sheep.
    Journal of developmental physiology, 1993
    Co-Authors: R. Alvaro, V. De Almeida, Saleh Al-alaiyan, May C. Robertson, B. Nowaczyk, Don Cates, Henrique Rigatto
    Abstract:

    : Umbilical cord occlusion in the presence of adequate oxygenation induces continuous Breathing and arousal in the chronic unanesthetized fetal sheep preparation. The mechanism responsible for this is unknown. We hypothesized that if a placental factor is responsible for the inhibition of Breathing in the Fetus, the administration of a placental extract while the Fetus is Breathing continuously after cord occlusion should reverse these changes. Thus, at about 10 min after the induction of continuous Breathing by cord occlusion, we administered a placental extract and three subfractions separated by ultrafiltration to 14 chronically instrumented fetal sheep at 133 +/- 1 day gestation. The Krebs solution in which the placental extract was prepared was used as control. Within two minutes of the infusion of the whole placental extract in the carotid artery of the Fetus, Breathing output (integral of EMGdi x f) diminished in all experiments and was completely abolished in 15/17 (88%). Krebs solution had no effect on Breathing. The infusion of subfractions of different molecular weight showed that the inhibition was primarily related to the subfraction between 3.5 and 10 kD. There were no significant changes in blood gas tensions, pH, blood pressure, and heart rate associated with the infusions of the extracts. The ECoG switched from low to high voltage in the majority of the experiments using whole extract and the subfraction 3.5 to 10 kD. These findings suggest that a placental factor, probably a peptide with a molecular weight between 3.5 and 10 kD, inhibits Breathing in fetal life.

R. Alvaro - One of the best experts on this subject based on the ideXlab platform.

  • Specificity of a placental factor inhibiting Breathing in fetal sheep
    Reproduction Fertility and Development, 1996
    Co-Authors: R. Alvaro, V. De Almeida, May C. Robertson, Don Cates, Virender Rehan, Zia Haider, A. Jansen, Henrique Rigatto
    Abstract:

    We have found previously that the infusion of a placental extract inhibits Breathing induced by 100% O2 plus umbilical cord occlusion in the fetal sheep, suggesting that a placental factor is responsible for the inhibition of fetal Breathing. To test whether this factor is specific to the placenta and whether it also inhibits spontaneous fetal Breathing (occurring in the absence of cord occlusion), we administered extracts from the placenta, muscle and liver of the pregnant ewe, extracts of fetal liver, and Krebs solution to 16 chronically instrumented fetal sheep at 135 +/- 5 days of gestation. Infusions were made during low-voltage electrocortical activity, 5 to 15 min after a switch from high voltage, when Breathing was well established. Within 90 s of the infusion of the placental extract in the carotid artery of the Fetus, Breathing decreased in 79% (33/42) of the experiments and was completely abolished in 71% (30/42) of them (P < 0.0001 compared with the other infusates). No apnoeas were observed with the Krebs solution (0/19) and the maternal muscle (0/20). Extracts of maternal and fetal liver abolished Breathing in only 17% (4/23) and 21% (6/29) of the experiments respectively (NS compared with Krebs solution). There were no significant changes in blood gas tensions, pH, blood pressure and heart rate associated with the infusion of the extracts. The electrocortical activity (ECoG) switched from low to high voltage in 50% of the experiments using placental extract compared with 0% with Krebs solution and maternal muscle, and with 9% and 17% with maternal and fetal liver respectively (P < 0.005). Breathing output (integral of EMGdi x f) during and after the infusions significantly decreased only with the placental extract. These findings indicate the presence of a factor produced by the placenta which inhibits fetal Breathing and may be responsible for the normal inhibition of Breathing observed in fetal life.

  • A placental extract inhibits Breathing induced by umbilical cord occlusion in fetal sheep.
    Journal of developmental physiology, 1993
    Co-Authors: R. Alvaro, V. De Almeida, Saleh Al-alaiyan, May C. Robertson, B. Nowaczyk, Don Cates, Henrique Rigatto
    Abstract:

    : Umbilical cord occlusion in the presence of adequate oxygenation induces continuous Breathing and arousal in the chronic unanesthetized fetal sheep preparation. The mechanism responsible for this is unknown. We hypothesized that if a placental factor is responsible for the inhibition of Breathing in the Fetus, the administration of a placental extract while the Fetus is Breathing continuously after cord occlusion should reverse these changes. Thus, at about 10 min after the induction of continuous Breathing by cord occlusion, we administered a placental extract and three subfractions separated by ultrafiltration to 14 chronically instrumented fetal sheep at 133 +/- 1 day gestation. The Krebs solution in which the placental extract was prepared was used as control. Within two minutes of the infusion of the whole placental extract in the carotid artery of the Fetus, Breathing output (integral of EMGdi x f) diminished in all experiments and was completely abolished in 15/17 (88%). Krebs solution had no effect on Breathing. The infusion of subfractions of different molecular weight showed that the inhibition was primarily related to the subfraction between 3.5 and 10 kD. There were no significant changes in blood gas tensions, pH, blood pressure, and heart rate associated with the infusions of the extracts. The ECoG switched from low to high voltage in the majority of the experiments using whole extract and the subfraction 3.5 to 10 kD. These findings suggest that a placental factor, probably a peptide with a molecular weight between 3.5 and 10 kD, inhibits Breathing in fetal life.

V. De Almeida - One of the best experts on this subject based on the ideXlab platform.

  • Specificity of a placental factor inhibiting Breathing in fetal sheep
    Reproduction Fertility and Development, 1996
    Co-Authors: R. Alvaro, V. De Almeida, May C. Robertson, Don Cates, Virender Rehan, Zia Haider, A. Jansen, Henrique Rigatto
    Abstract:

    We have found previously that the infusion of a placental extract inhibits Breathing induced by 100% O2 plus umbilical cord occlusion in the fetal sheep, suggesting that a placental factor is responsible for the inhibition of fetal Breathing. To test whether this factor is specific to the placenta and whether it also inhibits spontaneous fetal Breathing (occurring in the absence of cord occlusion), we administered extracts from the placenta, muscle and liver of the pregnant ewe, extracts of fetal liver, and Krebs solution to 16 chronically instrumented fetal sheep at 135 +/- 5 days of gestation. Infusions were made during low-voltage electrocortical activity, 5 to 15 min after a switch from high voltage, when Breathing was well established. Within 90 s of the infusion of the placental extract in the carotid artery of the Fetus, Breathing decreased in 79% (33/42) of the experiments and was completely abolished in 71% (30/42) of them (P < 0.0001 compared with the other infusates). No apnoeas were observed with the Krebs solution (0/19) and the maternal muscle (0/20). Extracts of maternal and fetal liver abolished Breathing in only 17% (4/23) and 21% (6/29) of the experiments respectively (NS compared with Krebs solution). There were no significant changes in blood gas tensions, pH, blood pressure and heart rate associated with the infusion of the extracts. The electrocortical activity (ECoG) switched from low to high voltage in 50% of the experiments using placental extract compared with 0% with Krebs solution and maternal muscle, and with 9% and 17% with maternal and fetal liver respectively (P < 0.005). Breathing output (integral of EMGdi x f) during and after the infusions significantly decreased only with the placental extract. These findings indicate the presence of a factor produced by the placenta which inhibits fetal Breathing and may be responsible for the normal inhibition of Breathing observed in fetal life.

  • A placental extract inhibits Breathing induced by umbilical cord occlusion in fetal sheep.
    Journal of developmental physiology, 1993
    Co-Authors: R. Alvaro, V. De Almeida, Saleh Al-alaiyan, May C. Robertson, B. Nowaczyk, Don Cates, Henrique Rigatto
    Abstract:

    : Umbilical cord occlusion in the presence of adequate oxygenation induces continuous Breathing and arousal in the chronic unanesthetized fetal sheep preparation. The mechanism responsible for this is unknown. We hypothesized that if a placental factor is responsible for the inhibition of Breathing in the Fetus, the administration of a placental extract while the Fetus is Breathing continuously after cord occlusion should reverse these changes. Thus, at about 10 min after the induction of continuous Breathing by cord occlusion, we administered a placental extract and three subfractions separated by ultrafiltration to 14 chronically instrumented fetal sheep at 133 +/- 1 day gestation. The Krebs solution in which the placental extract was prepared was used as control. Within two minutes of the infusion of the whole placental extract in the carotid artery of the Fetus, Breathing output (integral of EMGdi x f) diminished in all experiments and was completely abolished in 15/17 (88%). Krebs solution had no effect on Breathing. The infusion of subfractions of different molecular weight showed that the inhibition was primarily related to the subfraction between 3.5 and 10 kD. There were no significant changes in blood gas tensions, pH, blood pressure, and heart rate associated with the infusions of the extracts. The ECoG switched from low to high voltage in the majority of the experiments using whole extract and the subfraction 3.5 to 10 kD. These findings suggest that a placental factor, probably a peptide with a molecular weight between 3.5 and 10 kD, inhibits Breathing in fetal life.

May C. Robertson - One of the best experts on this subject based on the ideXlab platform.

  • Specificity of a placental factor inhibiting Breathing in fetal sheep
    Reproduction Fertility and Development, 1996
    Co-Authors: R. Alvaro, V. De Almeida, May C. Robertson, Don Cates, Virender Rehan, Zia Haider, A. Jansen, Henrique Rigatto
    Abstract:

    We have found previously that the infusion of a placental extract inhibits Breathing induced by 100% O2 plus umbilical cord occlusion in the fetal sheep, suggesting that a placental factor is responsible for the inhibition of fetal Breathing. To test whether this factor is specific to the placenta and whether it also inhibits spontaneous fetal Breathing (occurring in the absence of cord occlusion), we administered extracts from the placenta, muscle and liver of the pregnant ewe, extracts of fetal liver, and Krebs solution to 16 chronically instrumented fetal sheep at 135 +/- 5 days of gestation. Infusions were made during low-voltage electrocortical activity, 5 to 15 min after a switch from high voltage, when Breathing was well established. Within 90 s of the infusion of the placental extract in the carotid artery of the Fetus, Breathing decreased in 79% (33/42) of the experiments and was completely abolished in 71% (30/42) of them (P < 0.0001 compared with the other infusates). No apnoeas were observed with the Krebs solution (0/19) and the maternal muscle (0/20). Extracts of maternal and fetal liver abolished Breathing in only 17% (4/23) and 21% (6/29) of the experiments respectively (NS compared with Krebs solution). There were no significant changes in blood gas tensions, pH, blood pressure and heart rate associated with the infusion of the extracts. The electrocortical activity (ECoG) switched from low to high voltage in 50% of the experiments using placental extract compared with 0% with Krebs solution and maternal muscle, and with 9% and 17% with maternal and fetal liver respectively (P < 0.005). Breathing output (integral of EMGdi x f) during and after the infusions significantly decreased only with the placental extract. These findings indicate the presence of a factor produced by the placenta which inhibits fetal Breathing and may be responsible for the normal inhibition of Breathing observed in fetal life.

  • A placental extract inhibits Breathing induced by umbilical cord occlusion in fetal sheep.
    Journal of developmental physiology, 1993
    Co-Authors: R. Alvaro, V. De Almeida, Saleh Al-alaiyan, May C. Robertson, B. Nowaczyk, Don Cates, Henrique Rigatto
    Abstract:

    : Umbilical cord occlusion in the presence of adequate oxygenation induces continuous Breathing and arousal in the chronic unanesthetized fetal sheep preparation. The mechanism responsible for this is unknown. We hypothesized that if a placental factor is responsible for the inhibition of Breathing in the Fetus, the administration of a placental extract while the Fetus is Breathing continuously after cord occlusion should reverse these changes. Thus, at about 10 min after the induction of continuous Breathing by cord occlusion, we administered a placental extract and three subfractions separated by ultrafiltration to 14 chronically instrumented fetal sheep at 133 +/- 1 day gestation. The Krebs solution in which the placental extract was prepared was used as control. Within two minutes of the infusion of the whole placental extract in the carotid artery of the Fetus, Breathing output (integral of EMGdi x f) diminished in all experiments and was completely abolished in 15/17 (88%). Krebs solution had no effect on Breathing. The infusion of subfractions of different molecular weight showed that the inhibition was primarily related to the subfraction between 3.5 and 10 kD. There were no significant changes in blood gas tensions, pH, blood pressure, and heart rate associated with the infusions of the extracts. The ECoG switched from low to high voltage in the majority of the experiments using whole extract and the subfraction 3.5 to 10 kD. These findings suggest that a placental factor, probably a peptide with a molecular weight between 3.5 and 10 kD, inhibits Breathing in fetal life.

Don Cates - One of the best experts on this subject based on the ideXlab platform.

  • Specificity of a placental factor inhibiting Breathing in fetal sheep
    Reproduction Fertility and Development, 1996
    Co-Authors: R. Alvaro, V. De Almeida, May C. Robertson, Don Cates, Virender Rehan, Zia Haider, A. Jansen, Henrique Rigatto
    Abstract:

    We have found previously that the infusion of a placental extract inhibits Breathing induced by 100% O2 plus umbilical cord occlusion in the fetal sheep, suggesting that a placental factor is responsible for the inhibition of fetal Breathing. To test whether this factor is specific to the placenta and whether it also inhibits spontaneous fetal Breathing (occurring in the absence of cord occlusion), we administered extracts from the placenta, muscle and liver of the pregnant ewe, extracts of fetal liver, and Krebs solution to 16 chronically instrumented fetal sheep at 135 +/- 5 days of gestation. Infusions were made during low-voltage electrocortical activity, 5 to 15 min after a switch from high voltage, when Breathing was well established. Within 90 s of the infusion of the placental extract in the carotid artery of the Fetus, Breathing decreased in 79% (33/42) of the experiments and was completely abolished in 71% (30/42) of them (P < 0.0001 compared with the other infusates). No apnoeas were observed with the Krebs solution (0/19) and the maternal muscle (0/20). Extracts of maternal and fetal liver abolished Breathing in only 17% (4/23) and 21% (6/29) of the experiments respectively (NS compared with Krebs solution). There were no significant changes in blood gas tensions, pH, blood pressure and heart rate associated with the infusion of the extracts. The electrocortical activity (ECoG) switched from low to high voltage in 50% of the experiments using placental extract compared with 0% with Krebs solution and maternal muscle, and with 9% and 17% with maternal and fetal liver respectively (P < 0.005). Breathing output (integral of EMGdi x f) during and after the infusions significantly decreased only with the placental extract. These findings indicate the presence of a factor produced by the placenta which inhibits fetal Breathing and may be responsible for the normal inhibition of Breathing observed in fetal life.

  • A placental extract inhibits Breathing induced by umbilical cord occlusion in fetal sheep.
    Journal of developmental physiology, 1993
    Co-Authors: R. Alvaro, V. De Almeida, Saleh Al-alaiyan, May C. Robertson, B. Nowaczyk, Don Cates, Henrique Rigatto
    Abstract:

    : Umbilical cord occlusion in the presence of adequate oxygenation induces continuous Breathing and arousal in the chronic unanesthetized fetal sheep preparation. The mechanism responsible for this is unknown. We hypothesized that if a placental factor is responsible for the inhibition of Breathing in the Fetus, the administration of a placental extract while the Fetus is Breathing continuously after cord occlusion should reverse these changes. Thus, at about 10 min after the induction of continuous Breathing by cord occlusion, we administered a placental extract and three subfractions separated by ultrafiltration to 14 chronically instrumented fetal sheep at 133 +/- 1 day gestation. The Krebs solution in which the placental extract was prepared was used as control. Within two minutes of the infusion of the whole placental extract in the carotid artery of the Fetus, Breathing output (integral of EMGdi x f) diminished in all experiments and was completely abolished in 15/17 (88%). Krebs solution had no effect on Breathing. The infusion of subfractions of different molecular weight showed that the inhibition was primarily related to the subfraction between 3.5 and 10 kD. There were no significant changes in blood gas tensions, pH, blood pressure, and heart rate associated with the infusions of the extracts. The ECoG switched from low to high voltage in the majority of the experiments using whole extract and the subfraction 3.5 to 10 kD. These findings suggest that a placental factor, probably a peptide with a molecular weight between 3.5 and 10 kD, inhibits Breathing in fetal life.