TY - JOUR
T1 - Captopril inhibits the hydroosmotic effect of ADH in the cortical collecting tubule
AU - Rouse, D.
AU - Dalmeida, W.
AU - Williamson, F. C.
AU - Suki, Wadi N.
N1 - Funding Information:
abstract form in Kidney mt 27:264, 1985. Captopril used in this study was a gift from E.R. Squibb and Sons, Inc., Princeton, New Jersey, USA. The study was supported by grants from the National Institute of Health (AM21394 and AM37543) and from E.R. Squibb and Sons, Inc. The authors acknowledge the expert secretarial assistance of Mrs. Laura Pritchard.
PY - 1987
Y1 - 1987
N2 - Previous studies have shown that captopril (CP) inhibits ADH-stimulated osmotic water permeability (Pf) in the toad bladder by potentiating endogenous bradykinin (BK). The present studies examine the effect of CP on ADH-stimulated Pf in isolated, perfused rabbit cortical collecting tubules (CCT). CP (10-4 M) reversibly inhibited Pf, stimulated by maximal concentrations of ADH (10 μU/ml). Pretreatment of CCT's with 5 μM indomethacin, however, abolished the effect of CP. Inhibition of BK production by the kallikrein inhibitors, aprotinin and benzamidine, failed to enhance Pf stimulated by submaximal concentrations of ADH (2.5 μU/ml). Since ADH exerts its effects by activation of adenylyl cyclase (AC), further experiments were performed to identify the site at which CP inhibits this cascade. CP significantly inhibited forskolin (10-4 M) stimulated Pf; however, it had no effect on cyclic AMP (10-5 M) stimulated Pf, suggesting that the site of action is on the catalytic subunit or one of the GTP regulatory proteins of AC. To further localize the site of CP's action, CCT's were pre-incubated with pertussis toxin (0.5 μg/ml) to inactivate the inhibitory, guanosine triphosphate (GTP) regulatory protein, Gi. In these tubules, CP failed to inhibit the action of ADH. We conclude that CP stimulates prostaglandin production which in turn activates G(i) and inhibits AC activity. We further suggest that CP stimulates PG's directly, not via BK.
AB - Previous studies have shown that captopril (CP) inhibits ADH-stimulated osmotic water permeability (Pf) in the toad bladder by potentiating endogenous bradykinin (BK). The present studies examine the effect of CP on ADH-stimulated Pf in isolated, perfused rabbit cortical collecting tubules (CCT). CP (10-4 M) reversibly inhibited Pf, stimulated by maximal concentrations of ADH (10 μU/ml). Pretreatment of CCT's with 5 μM indomethacin, however, abolished the effect of CP. Inhibition of BK production by the kallikrein inhibitors, aprotinin and benzamidine, failed to enhance Pf stimulated by submaximal concentrations of ADH (2.5 μU/ml). Since ADH exerts its effects by activation of adenylyl cyclase (AC), further experiments were performed to identify the site at which CP inhibits this cascade. CP significantly inhibited forskolin (10-4 M) stimulated Pf; however, it had no effect on cyclic AMP (10-5 M) stimulated Pf, suggesting that the site of action is on the catalytic subunit or one of the GTP regulatory proteins of AC. To further localize the site of CP's action, CCT's were pre-incubated with pertussis toxin (0.5 μg/ml) to inactivate the inhibitory, guanosine triphosphate (GTP) regulatory protein, Gi. In these tubules, CP failed to inhibit the action of ADH. We conclude that CP stimulates prostaglandin production which in turn activates G(i) and inhibits AC activity. We further suggest that CP stimulates PG's directly, not via BK.
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U2 - 10.1038/ki.1987.285
DO - 10.1038/ki.1987.285
M3 - Article
C2 - 3323602
AN - SCOPUS:0023588120
SN - 0085-2538
VL - 32
SP - 845
EP - 850
JO - Kidney international
JF - Kidney international
IS - 6
ER -