title: Fluctuations of calcium, phosphorus, sodium, potassium, and chlorine in single alpha and beta cells during glucose perifusion of rat islets.
abstract: To study the relationship between islet hormonal secretion and intracellular content of five elements, a rat islet perifusion technique was used in 24 paired experiments. Control and experimental chambers each containing 100 islets, received 2.8 and 16.7 mM D-glucose, respectively. Effluent was collected frequently for hormone measurements. At eight different time intervals form 0--30 min islets were fixed and prepared for scanning electron microscopy. Over 900 unobscured alpha and beta cells were selected by size and shape criteria. Energy dispersive x-ray analysis was applied to each single cell to determine relative content of calcium (Ca), potassium (K), sodium (Na), chlorine (Cl), and phosphorus (P). Experimental chambers exhibited typical acute (0--9 min) and second phase (10--30 min) insulin secretion in association with suppression of glucagon release after 10 min. At 2 min an abrupt upward K spike in both alpha and beta cells was followed at 3--4 min with a 1.5- to 2-fold rise of Ca and a reciprocal decrease in K, Na, Cl, and P. From 3 to 30 min biphasic insulin secretion. Reduced alpha cell calcium after 6 min preceded suppression of glucagon secretion. After 2 min K related inversely to Ca content in both alpha and beta cells. These results could not be reproduced when D-galactose was substituted for D-glucose. We conclude that sequential changes of Ca content that are reciprocally related to K are predictive of beta cell insulin release and suppression of alpha cell glucagon secretion.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002713:Chlorine / Q000378:metabolism; D005260:Female; D005690:Galactose / Q000494:pharmacology; D005934:Glucagon / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D010758:Phosphorus / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D051381:Rats; D012964:Sodium / Q000378:metabolism
chemical_list: D007328:Insulin; D010758:Phosphorus; D002713:Chlorine; D005934:Glucagon; D012964:Sodium; D005947:Glucose; D011188:Potassium; D002118:Calcium; D005690:Galactose