Use of Liver Adenyl Cyclase for Assay of Glucagon in Human Gastro-intestinal Tract and Pancreas1

Abstract

Experimental conditions for assay of glucagon with cat liver adenyl cyclase are described. Negligible amounts of cyclic 3′,5′-AMP were produced in the absence of added hormone. The maximal response, sensitivity and steepness of slope of the titration curve were greater for glucagon than for epinephrine in this system. With use of this assay, activity previously reported to be present in dog gastric mucosa was characterized further as glucagon. Glucagon was also found to be present in the muscular layer of gastro-intestinal tissue. The concentration of glucagon in dog gastric mucosa (avg of 5.5 μg/g tissue extracted for fundic mucosa) at times equaled that of dog pancreas (7.3 Mg/g avg). Activity was found to be present in both the muscular and mucosal layers of human gastro-intestinal tissue and was characterized as glucagon. The concentration of glucagon in these tissues was about 2 μg/g, or about one eighteenth that in human pancreas. (Endocrinology75: 127, 1964)