The inhibition of human duodenal adenylate cyclase activity by Ca super(2+) and the effects of EGTA

• Published in: FEBS letters Vol. 327; no. 2; pp. 137 - 140
• Main Authors: Smith, JA, Griffin, M, Mireylees, SE, Long, R G
• Format: Journal Article
• Language: English
• Published: 01-01-1993
• ISSN: 0014-5793

This study demonstrates that the inhibition of adenylate cyclase activity by Ca super(2+) is enhanced in the presence of increasing [EGTA] (0, 0.3, 1, 2.5 mM) by 2 orders of magnitude. It has been established that this effect is not because of poor Ca super(2+) buffering by low [EGTA] or high Ca super(2+) binding by the membrane preparation. It is present irrespective of stimulus. We suggest the enhanced sensitivity of adenylate cyclase to Ca super(2+) induced by EGTA is caused by the Ca-EGTA complex being a more inhibitory species than Ca super(2+). Thus consideration of the effects of the Ca-EGTA complex should be made when interpreting the results from experiments involving Ca super(2+) and EGTA.