Chemically induced cardiovascular reflexes arising from the stomach of the cat

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Abstract
The potential for cardiovascular reflexes caused by the application of either bradykinin or capsaicin to the serosal or mucosal surface of the stomach was examined. After application to the serosa, bradykinin (10 .mu.g/ml) evoked increases in mean arterial pressure of 12 .+-. 2 mm Hg, heart rate of 5 .+-. 1 beats/min, left ventricular dP/dt (at 40 mm Hg developed pressure) of 305 .+-. 54 mm Hg/s and systemic vascular resistance of 0.04 .+-. 0.01 PRU [peripheral resistance U]. Capsaicin (200 .mu.g/ml) caused similar cardiovascular responses. There were no cardiovascular responses when either substance was applied to the gastric mucosa. The responses to both chemicals were abolished by celiac ganglionectomy but not by bilateral vagotomy. To determine whether the cardiovascular responses evoked by bradykinin were caused by smooth muscle contraction, the increases in gastric smooth muscle tension and blood pressure elicited by bradykinin, bethanechol or acetylcholine was compared. Bethanechol and acetylcholine caused greater increases in tension than bradykinin, whereas bradykinin evoked greater increases in blood pressure than either bethanechol or acetylcholine. Stimulation of gastric afferents by capsaicin or bradykinin causes cardiovascular reflexes, primarily through activation of chemosensitive receptors.