Vagal involvement in the pressor responses to cranial artery infusions of bradykinin in anaesthetised greyhounds.
In anaesthetised greyhounds, vertebral and carotid artery infusions of bradykinin increased blood pressure whereas intravenous infusions caused a decrease. With each route of administration, heart rate and cardiac output increased while total peripheral resistance fell. With cranial artery infusions, the consecutive pretreatments of propranolol, phentolamine and vagal cooling resulted in a progressive reduction in the heart rate responses and conversion of the pressor to depressor responses. The responses to intravenous infusions of bradykinin were little changed. In contrast, when the initial pretreatment was interruption of vagal transmission, cranial artery infusions of bradykinin were at once depressor and the depressor response to intravenous infusions immediately enhanced. Subsequent propranolol and phentolamine were without further effect on the blood pressure responses although propranolol did reduce the tachycardia responses. It is concluded that while the tachycardia induced by cranial artery infusions of bradykinin has both cardiac sympathetic and vagal withdrawal components, the hypertensive action is mediated by an increase in cardiac output due largely to withdrawal of cardiac vagal tone.
D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001920:Bradykinin / Q000008:administration & dosage / Q000494:pharmacology*; D003080:Cold Temperature; D004285:Dogs; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D007269:Injections, Intra-Arterial; D007275:Injections, Intravenous; D008297:Male; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D014628:Vagotomy; D014630:Vagus Nerve / Q000502:physiology*
D011433:Propranolol; D001920:Bradykinin; D010646:Phentolamine