Vagotomy impairs pentagastrin-induced relaxation of canine gastric fundus

In eight dogs, a separated, vagally innervated pouch was made from the gastric fundus. Electrodes were implanted on the pouch, and an antral gastric fistula was created through which gastric juice was drained externally during all tests. After recovery, the fasted, conscious dogs received intravenous infusions of 154 mM NaCl to which randomly selected doses of pentagastrin were intermittently added while intraluminal pressure and electric activity of the distended pouch were recorded. Transthoracic vagotomy was then performed, and the dogs were restudied. Before vagotomy, pentagastrin decreased the amplitude of the phasic changes in intraluminal pressure and of the bursts of spiking potentials of the pouch. The D50 for inhibition of mean intrapouch pressure was 4.2 ng/kg per min. After vagotomy, pentagastrin still decreased intrapouch pressure and inhibited fundal spikes, but larger doses were required to produce equivalent decreases in pressure. The D50 was 41.4 ng/kg per min after vagotomy. Our conclusion is that pentagastrin-induced relaxation of the canine gastric fundus is impaired, but not abolished, by vagotomy.