THE EFFECT OF STIMULATING CAROTID-BODY CHEMORECEPTORS ON GASTRIC-MUCOSAL BLOOD-FLOW IN THE RAT

The high incidence of gastric ulceration has been recognised in people living at high altitude and in patients with respiratory insufficienc y. The carotid body chemoreceptors (CB) are activated both at high alt itude and in respiratory insufficiency. The purpose of this study was to evaluate the effect of CB stimulation on gastric mucosal blood flow . Experiments were performed on male Wistar rats (280-300 g), anaesthe tised with chloral hydrate, artificially ventilated. Gastric mucosal b lood flow (GMBF) was measured using laser Doppler flowmeter. Substitut ing 8% O-2 for room air caused significant increase in gastric mucosal vascular resistance (GMVR) from 3.2 mmHg/mL/min/100 g +/- 0.09 SEM to 5.5 mmHg/mL/min/100 g +/- 0.26 SEM (p < 0.01) with concomitant decrea se in GMBF from 29.1 mL/min/100 g +/- 0.8 SEM to 14.1 mL/min/100g +/- 0.9 SEM (p < 0.001). Direct stimulation of CB by injection of acid sal ine (pH 6.825) into the common carotid artery lead to the comparable c hanges in GMVR and GMBF as during hypoxia. A decrease in GMBF during h ypoxia was abolished by either surgical denervation of CBs or alpha-re ceptor blockade with phentolamine. A decrease in GMBF plays a role in mucosal damage. We postulate that stimulation of CB might be a link be tween hypoxia and gastric ulceration.