Adrenergic stimulation of pepsinogen release from rabbit isolated gastric glands

Isolated gastric glands from the rabbit were used for studying the effect of catecholamines on the release of pepsinogen. Isoprenaline, adrenaline and noradrenaline stimulated pepsinogen release in a dose-dependent manner with similar maximal effects, but isoprenaline was significantly more potent than the other two agonists. The effect was mediated through beta-adrenoceptors, since the response was inhibited by the beta-adrenoceptor antagonist, propranolol, and since the alpha-adrenoceptor agonist, phenylephrine, was without effect in the concentration range 0.01 - 10 microM. Concentration-response curves for isoprenaline were shifted to the right in parallel by increasing doses of propranolol, and maximal response was not influenced by propranolol per se, which indicates a competitive type of antagonism. A Schild plot showed a pA2-value for propranolol of 7.70 and the slope of the regression line was 1.02. Studies with the beta 1-selective antagonist pafenolol and the beta 2-selective antagonist ICI 118.551 demonstrated that isoprenaline acted through beta 1-adrenoceptors. The results suggest an adrenergic component in the control of the peptic cells in rabbit gastric mucosa.