Changes in the baroreflex during pregnancy in conscious dogs: heart rate and hormonal responses.
This study was performed to test the hypothesis that reflex increases in heart rate, PRA, and plasma concentrations of vasopressin, angiotensin-II, ACTH, and cortisol are reduced during pregnancy. The hypothesis was tested by measuring, in pregnant and nonpregnant conscious dogs, changes in arterial and atrial pressures, heart rate, and plasma hormone concentrations during 30-min infusions of three doses of nitroprusside (1, 2, and 4 micrograms/kg.min). Between-group differences were determined by comparing the relationships between arterial or atrial pressure and plasma hormone concentrations. Hypotension-induced increases in heart rate and plasma levels of vasopressin, ACTH, and cortisol were blunted when the dogs were pregnant. In contrast, reflex increases in PRA and angiotensin-II were increased. These results indicate that the activity of the baroreceptor reflex is altered during pregnancy in dogs.
Department of Physiology, Oregon Health Sciences University, Portland 97201-3098.
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Brooks
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Keil
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000804:Angiotensin II / Q000097:blood*; D000818:Animals; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006854:Hydrocortisone / Q000097:blood; D009599:Nitroprusside; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D011863:Radioimmunoassay; D014667:Vasopressins / Q000097:blood*
D014667:Vasopressins; D000804:Angiotensin II; D009599:Nitroprusside; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone