ISSN:
1432-2013
Keywords:
Collecting duct principal cell culture
;
High conductance K+ channel
;
Renal K+ secretion
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Using the patch clamp technique, one type of K+ channel was identified in the apical cell membrane of cultured principal cells of rabbit renal collecting ducts in the cell-attached or excised-patch configuration. The channel was highly selective for K+ over Na+ (typically 30-70-fold) and had a conductance of 180, SD±39 pS (n=6), referred to a situation of 140 mmolar K+-Ringer solution present on either surface of the patch membrane. Channel activity was completely blocked by Ba2+ (5 mmol/l) and partially inhibited by Na+. The latter was evidenced by a deviation from Goldman rectification at high cytoplasm-positive membrane potentials, which was observed when Na+ competed with K+ for channel entrace from the cytoplasmic surface. Channel open probability depended strongly on membrane voltage and cytoplasmic Ca2+ concentration. Open-close kinetics exhibited double exponential behaviour, with a strong voltage dependence of the slow open time constant. Infrequently also a substate conductance level was identified. The voltage and calcium dependence suggest that the channel plays a role in adjusting K+ secretion to Na+ absorption in the fine regulation of cation excretion in renal collecting ducts.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02181471
Permalink
