Inhibitory effects of loading with the calcium-chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) on amylase release and cellular ATP level in rat parotid cells.
Rat parotid cells were loaded with the Ca2(+)-chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), by incubation with the acetoxymethyl ester of BAPTA (BAPTA-AM). The BAPTA loading inhibited amylase release induced by beta-adrenergic receptor stimulation without affecting the basal release, and the IC50 value was 25 microM. Incubation of cells with BAPTA-AM also suppressed cellular ATP levels considerably. At 100 microM BAPTA-AM, the ATP level fell to about 50% of the control. A decrease in ATP levels by incubation with oligomycin, a mitochondrial inhibitor, correlated well with the inhibition of amylase release. Although these results do not exclude the possibility that cytosolic free Ca2+ is involved in the regulation of cyclic AMP-mediated amylase release, they suggest that the amylase release inhibition with BAPTA loading may be due, in part, to a decrease in cellular ATP levels. Therefore, the exact mode of the BAPTA action must be interpreted with caution.
Department of Dental Pharmacology, School of Dentistry, Higashi-Nippon-Gakuen University, Hokkaido, Japan.
Y
Y
Tojyo
Y
Y
Matsumoto
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000681:Amylases / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology / Q000031:analogs & derivatives; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D010306:Parotid Gland / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D004533:Egtazic Acid; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D000681:Amylases; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D007545:Isoproterenol