Differing significance of Na(+)-Ca2+ exchange in the regulation of cytosolic Ca2+ in rat exocrine gland acini and cardiac myocytes.
In order to compare the importance of Na(+)-Ca2+ exchange in the regulation of cytosolic Ca2+ concentration (Ca2+i), acini obtained from rat pancreas and submandibular glands as well as cardiac myocytes were loaded with Na+ by inhibition of Na(+)-K+ ATPase activity then loaded with fura-2. In the exocrine tissues, incubation in K(+)-free buffer or with ouabain had no substantial effect on resting Ca2+i or on the changes in Ca2+i following exposure to carbachol as compared with acini incubated under control conditions. In contrast, rat cardiac myocytes, treated identically, showed marked changes in Ca2+i under resting and stimulated conditions as compared with controls. We conclude that the Na(+)-Ca2+ exchange systems of rat pancreatic and submandibular gland acini contribute little to the overall regulation of Ca2+i at rest during cholinergic stimulation.
Hurley
T W
TW
Department of Child Health, University of Missouri School of Medicine, Columbia 65212.
Dale
W E
WE
Rovetto
M J
MJ
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism*; D005088:Exocrine Glands / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D066298:In Vitro Techniques; D007474:Ion Exchange; D009206:Myocardium / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D010179:Pancreas / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D010275:Parasympathetic Nervous System / Q000166:cytology / Q000502:physiology; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013363:Submandibular Gland / Q000166:cytology / Q000201:enzymology / Q000378:metabolism
D002217:Carbachol; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium