Arterial baroreflex inhibition by gastric distension in rats: mediation by splanchnic afferents

Integrative Comp. Physiol. 29): R985-R994, 1991.-Arterial baroreflexes are known to be reset during activation of defense area and somatosensory receptors-afferents. Here we report that viscerosensory activation also inhibits the baroreflexes. In chloralose-urethan-anesthetized, succinylcholine-immobilized, and artificially ventilated rats, the aortic depressor nerve was electrically stimulated while propranolol was continuously in-fused to elicit baroreflex hypotension (BH) and baroreflex vagal bradycardia (BVB). Hydraulic distension of the stomach with warm 0.9 % NaCl solution was found to suppress BVB and BH, with a threshold intraluminal pressure at times GmmHg. The gastric distension also suppressed BH in atropinized rats, sug-gesting that inhibition involved not only cardiac but also vas-cular components of baroreflexes. Bilateral splanchnectomy largely attenuated the inhibition, whereas bilateral subdia