ISSN:
1432-1424
Keywords:
epithelial transport
;
apical Na permeability of frog skin
;
fluctuation analysis
;
extrinsic blockers
;
amiloride analogs
;
triamterene
;
triaminopyrimidine
;
dose-response curves
;
competition kinetics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary Fluctuation analysis of Na current passing the apical membrane in the skin ofRana ridibunda was used to study the kinetics of Na-channel blocking by several organic cations present in the outer solution together with 60mm Na. The ratios of the apparent off-rate and on-rate constants (the microscopic inhibition constants) thus obtained for triamterene, triaminopyrimidine (TAP), 5,6-diCl-amiloride, 5H-amiloride and amiloride itself are found to be in the mean about sevenfold smaller than the corresponding inhibition constants obtained from macroscopic dose-response curves. The apparent discrepancy is explicable by competition of the organic blocker with the channel block by Na ions (the self-inhibition effect). The type of interaction between extrinsic blockage and self-inhibition may be purely competitive or mixed. However, in case of mixed inhibition the competitive component must dominate the noncompetitive component by at least seven to one.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01870366
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