Beta-adrenergic-induced calcium efflux in rat parotid gland. Is mitochondrial Na+/Ca2+ exchange involved?
The effects of diltiazem were examined on 45Ca efflux in rat parotid glands. First, we showed that mitochondrial Na+/Ca2+ exchange occurs in rat parotid glands and that diltiazem inhibited the mitochondrial Na(+)-dependent calcium efflux. We also confirmed that in rat parotid gland, diltiazem did not modify calcium movements at plasma membrane level. Secondly, we tested the effects of diltiazem on pieces of parotid glands. Diltiazem alone induced 45Ca efflux from parotid lobules. When the effect of diltiazem was tested on isoproterenol-induced 45Ca efflux, the effects of the two drugs were less than additive. By comparison, diltiazem did not modify carbachol induced 45Ca efflux. Diltiazem was able to induce calcium efflux from an intracellular calcium pool, which is not the IP3 sensitive one. These data support the previous hypothesis that isoproterenol and carbachol do not mobilize the same calcium pool. Although we did not precisely determine the calcium pool sensitive to beta-adrenergic stimulation, we cannot rule out the hypothesis that mitochondria would be that store.
Dreux
C
C
Biochimie des transports cellulaires, CNRS URA 1116, Université Paris XI, Orsay, France.
Huleux
C
C
Eboué
D
D
Rossignol
B
B
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004110:Diltiazem / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010306:Parotid Gland / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger
D002121:Calcium Channel Blockers; D002352:Carrier Proteins; D007476:Ionophores; D011943:Receptors, Adrenergic, beta; D019831:Sodium-Calcium Exchanger; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D012964:Sodium; D004110:Diltiazem; D002118:Calcium