Activation of gastric afferent fibers increases coronary arterial resistance in anesthetized dogs

Abstract

Stimulation of chemically sensitive receptors in the stomach with capsaicin is known to reflexly increase heart rate, arterial pressure, left ventricular contractility, and systemic vascular resistance. What is not known, however, is if activating these gastric afferents can also evoke reflex changes in coronary arterial resistance. Therefore, in 24 chloralose-anesthetized dogs, we used a Gregg cannula and a constant flow preparation to assess left circumflex coronary arterial (LCCA) resistance while stimulating chemically sensitive gastric receptors with capsaicin. Capsaicin (60 μg), applied topically to the serosal surface of the stomach, produced significant ( P < 0.05) increases in heart rate (8 ± 2 bpm), mean arterial pressure (22 ± 1 mm Hg), LCCA pressure (7 ± 1 mm Hg), and LCCA resistance (0.30 ± 0.04 mm Hg/ml/min). These responses were still present after bilateral thoracic vagotomy, but were eliminated by bilateral thoracic splanchnicotomy. α-Adrenergic blockade eliminated and β-adrenergic blockade enhanced the increases in LCCA pressure and resistance that were evoked by capsaicin. Thus, stimulating chemically sensitive receptors in the stomach can reflexly increase coronary arterial resistance by α-adrenergic vasoconstriction. The possibility exists, therefore, that physiological or pathological events which activate gastric afferents can affect reflexly the coronary circulation.