Evidence against participation of V2 receptors in the increase of cerebral blood flow during hypoxemia in the rat.
Cerebral blood flow (CBF) and cerebral utilization of oxygen (CMRO2) were studied in anesthetized and artificially ventilated rats during normoxemia and hypoxemia before and during intravenous infusion of a selective blocker of V2 vasopressinergic receptors (d(CH2)5 [D-Ile2,Abu4] AVP, 15 micrograms/kg per hour i.v.). CBF was measured by means of the intracarotid 133-Xe injection method. CMRO2 was calculated from the oxygen arteriovenous difference using the Fick principle. Infusion of V2 antagonist did not influence CBF, CMRO2 or blood pressure (BP) during normoxia. It also did not change the response of cerebral circulation to hypoxemia. Increase in CBF and decrease in cerebrovascular resistance (CVR) during hypoxemia were similar during the infusion of V2 blocker or without it. However, the decrease in BP observed during hypoxemia in the control group of rats was prevented in the group of animals which were infused with V2 blocker.
Koźniewska
E
E
Department of Clinical and Applied Physiology, School of Medicine, Warsaw, Poland.
Oseka
M
M
D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001127:Arginine Vasopressin / Q000502:physiology / Q000031:analogs & derivatives; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D011945:Receptors, Angiotensin / Q000502:physiology*; D017483:Receptors, Vasopressin; D014655:Vascular Resistance / Q000187:drug effects; D014667:Vasopressins / Q000494:pharmacology*
D057911:Angiotensin Receptor Antagonists; D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; D014667:Vasopressins; D001127:Arginine Vasopressin; C056186:argipressin, beta-mercapto-beta,beta-cyclopentamethylenepropionic acid(1)-Ile(2)-Abu(4)-