Histamine release in vivo by pentagastrin from the canine stomach

The effect of intragastric arterial infusion of pentagastrin on gastric histamine release was evaluated in mongrel dogs in vivo. Histamine secretory rates were evaluated by measuring the arterial and gastric venous plasma histamine concentrations at 0, 5, 10, 15 and 20 min into pentagastrin infusions, and gastric blood flow was continuously monitored. Histamine secretory rates were calculated by subtracting the arterial from the venous histamine concentrations and multiplying the difference by gastric plasma flow. Two separate 20-min infusions of pentagastrin, separated by 60 min, resulted in a peak of histamine release in 5 to 10 min that returned to base line within 20 min. During the first infusion, histamine release peaked at 179 ng/min, whereas, during the second infusion, histamine peaked at 125 ng/ml. The increase in gastric blood flow to pentagastrin correlated with the increases in histamine release. Somatostatin infused into the gastric artery to attain a concentration of 10 nM, a concentration that results in the inhibition of gastric acid secretion, abolished the gastric histamine release to pentagastrin. In addition, somatostatin also attenuated the gastric vasodilation to pentagastrin. Our data indicate that, in the in vivo dog model, pentagastrin can cause a pulsed release of gastric histamine, and somatostatin inhibits this release of histamine.