Regional blood flows and cardiac function changes induced by angiotensin II in conscious dogs.
Hemodynamic properties of angiotensin (ANG) II 1, 5, 10 and 100 ng/kg i.v. and 10, 100 and 1000 ng/kg i.v.t. were assessed in conscious dogs. ANG II i.v. produced a dose-dependent pressor response (59 +/- 5-124 +/- 16 mmHg) and renal vasoconstriction (1.3 +/- 0.4-96 +/- 32 mmHg/ml/min). Ganglionic blockade (chlorisondamine 2 mg/kg i.v.) diminished mean arterial responses without altering peptide effects on renal circulation. At the highest dose, ANG II i.v. induced cardiac stimulation: increased heart rate (75 +/- 4-115 +/- 6 beats/min), cardiac output (2.0 +/- 0.1-2.4 +/- 0.2 l/min), dP/dt (2308 +/- 181-2773 +/- 173 mmHg/sec) and coronary blood flow (49 +/- 10-96 +/- 23 ml/min). Although with chlorisondamine cardiac response was more pronounced, subsequent beta blockade abolished it. Concomitantly, an isolated increase in plasma epinephrine was recorded (63 +/- 8-1505 +/- 354 pg/ml). A pressor response (59 +/- 8-89 +/- 13 mmHg) and renal vasoconstriction (1.1 +/- 0.1-2.2 +/- 0.5 mmHg/ml/min) were also produced by ANG II i.v.t. at the highest dose. These centrally mediated changes were prevented by chlorisondamine. Our study demonstrates 1) i.v. ANG II-mediated pressor responses are dependent on direct and indirect components, the relative contribution of each being dependent on the regional circulation; ANG II i.v. also produced a biphasic cardiac response--an initial centrally mediated depression and a secondary stimulation dependent on epinephrine via cardiac beta receptors and 2) i.v.t. ANG II-mediated pressor effects are essentially indirect. Finally, no evidence was found to support the role of vasopressin in ANG II effects.
Doursout
M F
MF
Department of Anesthesiology, Baylor College of Medicine, Houston, Texas.
Chelly
J E
JE
Hartley
C J
CJ
Szilagyi
J
J
Montastruc
J L
JL
Buckley
J P
JP
D000804:Angiotensin II / Q000008:administration & dosage / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002714:Chlorisondamine / Q000494:pharmacology; D003326:Coronary Circulation / Q000187:drug effects; D004285:Dogs; D004837:Epinephrine / Q000097:blood; D006321:Heart / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007275:Injections, Intravenous; D017483:Receptors, Vasopressin; D012079:Renal Circulation / Q000187:drug effects
D057911:Angiotensin Receptor Antagonists; D017483:Receptors, Vasopressin; D000804:Angiotensin II; D001127:Arginine Vasopressin; D002714:Chlorisondamine; D004837:Epinephrine