The inhibition of cyclic AMP-mediated exocytosis from rat parotid cells by calcium chelation is due to depression of cellular ATP.
The role of second messenger calcium in cAMP-mediated exocytosis from parotid cell aggregates has been assessed following extracellular (ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA] and intracellular (quin2) calcium chelation. Only in the former case was inhibition (60-70%) of isoproterenol- and N6,O2-dibutyryl cAMP-stimulated amylase release observed. This inhibition was accompanied by a 70% decrease in cellular ATP levels. Depression of ATP levels with mitochondrial inhibitors was also correlated with inhibition of amylase secretion. Overall, our results suggest that depletion of cellular Ca2+ with EGTA leads to an inhibition of mitochondrial function and that these experimental conditions are therefore inappropriate for the evaluation of the role of cytosolic Ca2+ transients during stimulus-secretion coupling.
Hincke
M T
MT
Department of Anatomy, Faculty of Health Sciences, University of Ottawa, Canada.
D000634:Aminoquinolines / Q000494:pharmacology*; D000681:Amylases / Q000378:metabolism; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology*; D005089:Exocytosis; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009840:Oligomycins / Q000494:pharmacology; D010306:Parotid Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000634:Aminoquinolines; D009840:Oligomycins; D004533:Egtazic Acid; D003994:Bucladesine; D000242:Cyclic AMP; D000681:Amylases; D007545:Isoproterenol; C035739:Quin2; D002118:Calcium