Lack of cardiovascular and vasopressin responses to human relaxin in conscious, late-pregnant rats.
Measurements of arterial pressure, heart rate, and plasma vasopressin were obtained in unanesthetized late-pregnant rats after administration of human relaxin (hRlx) alone or in conjunction with hemorrhage. Forty-two timed-pregnant rats were prepared with chronic femoral cannulas on the 17th day of pregnancy for measurements on the 19th day. In three separate sets of experiments, mean arterial pressure and heart rate were measured for 10 min before administration of 2 mg/kg hRlx, 100 micrograms/kg hRlx, or vehicle and for 20 h thereafter; plasma vasopressin was determined 20 min before and 3 min after administration of hRlx or vehicle and 20 min after performing a 15-ml/kg 3-min hemorrhage. Neither mean arterial pressure nor heart rate was significantly different among rats administered 2 mg/kg hRlx, 100 micrograms/kg hRlx, or vehicle. Plasma vasopressin was not significantly different among rats administered 2 mg/kg hRlx, 100 micrograms/kg hRlx, or vehicle. The decreases and subsequent compensatory changes in mean arterial pressure and heart rate after hemorrhage and the increases in plasma vasopressin were not significantly different among rats administered vehicle or hRlx.
Ward
D G
DG
H.M. Ward Memorial Laboratory, Valley Home, Virginia 95384.
Cronin
M J
MJ
Baertschi
A J
AJ
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006470:Hemorrhage / Q000097:blood / Q000503:physiopathology; D006801:Humans; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012065:Relaxin / Q000097:blood / Q000494:pharmacology*; D014667:Vasopressins / Q000097:blood*
D014667:Vasopressins; D012065:Relaxin