Pressor contributions from angiotensin and vasopressin after polyethylene glycol.
Isosmotic volume depletion was induced by subcutaneous injection of 5 ml of polyethylene glycol (PEG; 20 M; 30%) in Long-Evans rats and in rats deficient in hypothalamic vasopressin (Brattleboro rats). In the PEG-treated Long-Evans rats, captopril caused a hypotension that was greater than that seen in saline-injected controls. Pretreatment with the vasopressin (V1 receptor) antagonist d(CH2)5DAVP did not, itself, cause a fall in blood pressure, but it enhanced the hypotensive effect of captopril in the PEG-treated Long-Evans rats. The PEG-treated Brattleboro rats had similar resting blood pressures to the PEG-treated Long-Evans rats, but in the former group, captopril caused a more profound and progressive hypotension than was seen in any of the present experimental regimes used in the Long-Evans rats. This suggests that, during hypovolemia induced by PEG, Brattleboro rats were either more dependent on the renin-angiotensin system for the maintenance of arterial blood pressure than were Long-Evans rats treated acutely with a vasopressin (V1) receptor antagonist or less able to recruit sympathoadrenal mechanisms to compensate for the sudden loss of the renin-angiotensin system.
D000804:Angiotensin II / Q000502:physiology*; D000818:Animals; D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D001810:Blood Volume; D002216:Captopril / Q000494:pharmacology; D002319:Cardiovascular System / Q000187:drug effects; D008297:Male; D010425:Pentolinium Tartrate / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000494:pharmacology*; D051381:Rats; D011910:Rats, Brattleboro; D011919:Rats, Inbred Strains; D014667:Vasopressins / Q000502:physiology*
D014667:Vasopressins; D000804:Angiotensin II; D001127:Arginine Vasopressin; D011092:Polyethylene Glycols; C025044:argipressin, beta-mercapto-beta,beta cyclopentamethylenepropionic acid(1)-; D010425:Pentolinium Tartrate; D002216:Captopril