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Amiloride‐sensitive sodium channels in rabbit and guinea‐pig gall‐bladder.
Author(s) -
Cremaschi D,
Meyer G
Publication year - 1982
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1982.sp014174
Subject(s) - amiloride , apical membrane , guinea pig , chemistry , biophysics , lumen (anatomy) , ion transporter , sodium , gall , epithelial polarity , epithelial sodium channel , membrane , endocrinology , medicine , biology , biochemistry , botany , organic chemistry
1. The effects of low amiloride concentrations (less than 2.5 x 10(‐5) M) on the apical membrane (Vm) and transepithelial (Vms) potential differences, transepithelial resistance (Rep) and apical/basolateral membrane resistance ratio (Rm/Rs) have been determined in the gall‐bladders of the rabbit and guinea‐pig. 2. Vm was hyperpolarized, Vms decreased towards negative values, Rm/Rs increased, but Rep remained unchanged. 3. K+ selectivity of the apical membrane was also checked by increasing luminal K+ concentration from 5.9 to 29.4 mM; the corresponding change in the apical electromotive force was much higher in the rabbit than in the guinea‐pig. 4. Pre‐incubations with Cl‐‐and HCO3‐‐free salines did not modify K+ selectivity in the rabbit, but nearly doubled it in the guinea‐pig. 5. Pre‐incubations with control solutions containing 10(‐5) M‐amiloride in the lumen converted the apical membrane of rabbit gall‐bladder into a perfectly K+‐perm‐selective membrane; the same results were obtained in the guinea‐pig only on bathing the tissue with Cl‐‐ and HCO3‐‐free salines together with 10(‐5) M‐amiloride. 6. It is suggested that in the apical membrane of rabbit gall‐bladder K+ and Na+ conductances exist, whereas in guinea‐pig gall‐bladder both K+, Na+ and anion (Cl‐ and/or HCO3‐) conductances are present; in both species conductive Na+ pathways are inhibited by amiloride. .