Quantitative analysis of the structural events associated with antidiuretic hormone-induced volume reabsorption in the rabbit cortical collecting tubule

1984 ◽  
Vol 79 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Kevin L. Kirk ◽  
James A. Schafer ◽  
Donald R. DiBona
Keyword(s):  
Quantitative Analysis ◽  
Antidiuretic Hormone ◽  
Collecting Tubule ◽  
Rabbit Cortical Collecting Tubule ◽  
Cortical Collecting Tubule

Amiloride-sensitive sodium channels in rabbit cortical collecting tubule primary cultures

1991 ◽  
Vol 261 (6) ◽  
pp. F933-F944 ◽  
Author(s):  
B. N. Ling ◽  
C. F. Hinton ◽  
D. C. Eaton
Keyword(s):  
High Selectivity ◽  
Primary Cultures ◽  
Principal Cell ◽  
Na Channel ◽  
Open Probability ◽  
Inward Current ◽  
Collecting Tubule ◽  
Apical Membranes ◽  
Rabbit Cortical Collecting Tubule ◽  
Cortical Collecting Tubule

Patch-clamp methodology was applied to principal cell apical membranes of rabbit cortical collecting tubule (CCT) primary cultures grown on collagen supports in the presence of aldosterone (1.5 microM). The most frequently observed channel had a unit conductance of 3-5 pS, nonlinear current-voltage (I-V) relationship, Na permeability (PNa)-to-K permeability (PK) ratio greater than 19:1, and inward current at all applied potentials (Vapp) less than +80 mV (n = 41). Less frequently, an 8- to 10-pS channel with a linear I-V curve, PNa/PK less than 5:1, and inward current at Vapp less than +40 mV was also observed (n = 7). Luminal amiloride (0.75 microM) decreased the open probability (Po) for both of these channels. Mean open time for the high-selectivity Na+ channel was 2.1 +/- 0.5 s and for the low-selectivity Na+ channel was 50 +/- 12 ms. In primary cultures grown without aldosterone the high-selectivity Na+ channel was rarely observed (1 of 32 patches). Lastly, a 26- to 35-pS channel, nonselective for Na+ over K+, was not activated by cytoplasmic Ca2+ or voltage nor inhibited by amiloride (n = 17). We conclude that under specific growth conditions, namely permeable transporting supports and chronic mineralocorticoid hormone exposure, principal cell apical membranes of rabbit CCT primary cultures contain 1) both high-selectivity and low-selectivity, amiloride-inhibitable Na+ channels and 2) amiloride-insensitive, nonselective cation channels.

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