Abstract
FUJITA, Y., KAWAJI, K., MORIYA, T., MATOBA K., ISHII, K., YAJIMA, Y. and OKABE, H. Role of Calcium in Suppression of Glucagon Release from Isolated Diabetic Rat Pancreata. Tohoku J. exp. Med., 1988, 154 (2), 185-193 -To investigate the role of extracellular Ca2+ (Ca2+) in suppression of glucagon release in diabetic animals, pancreata were isolated from streptozotocin-diabetic rats and perfused with a 15mM glucose solution containing one of the following: (1) Ca2+ 2.1mM and insulin 22μU/ml, (2) Ca2+ 2.1mM and insulin 110μU/ml, (3) Ca2+ 2.1mM and insulin (-) or (4) Ca2+ 0.2mM and insulin 110μU/ml. Although perfusion with 22μU/ml of insulin did not alter glucagon release, perfusion with 110μU/ml of insulin in the presence of Ca2+ and glucose significantly reduced the release of glucagon from 1.9±0.3ng/min to 1.2±0.3ng/min for the first 3min. The absence of insulin enhanced glucagon release from the baseline level of 1.0± 0.1ng/min to 1.6±0.3ng/min at 11min and to 1.4±0.2ng/min at 21min. Deprivation of Ca2+ in the perfusate also enhanced glucagon release from the baseline level of 0.8±0.1ng/min to 1.2±0.3ng/min for the first 4min. It is concluded that insulin suppresses glucagon release and Ca2+ is needed for the suppression of glucagon release in the presence of both insulin and glucose in streptozotocin-diabetic rat pancreata.
