Regulation of principal cell pH by Na/H exchange in rabbit cortical collecting tubule

1992 ◽  
Vol 125 (1) ◽  
Author(s):  
RandiB. Silver ◽  
Gustavo Frindt ◽  
LawrenceG. Palmer
Keyword(s):  
Principal Cell ◽  
Cell Ph ◽  
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.

Effects of calcium on ADH action in the cortical collecting tubule perfused in vitro

1982 ◽  
Vol 243 (5) ◽  
pp. F481-F486
Author(s):  
S. Goldfarb
Keyword(s):  
Hydraulic Conductivity ◽  
Water Flow ◽  
Collecting Tubule ◽  
Bath Water ◽  
Mammalian System ◽  
Rabbit Cortical Collecting Tubule ◽  
Cortical Collecting Tubule

To test the effects of calcium on ADH action in an in vitro mammalian system, the rabbit cortical collecting tubule was studied. After 25 microunits/ml ADH (n=8) in the presence of 1.25 mM calcium bath, water flow (Jv) rose to 1.56 +/- 0.34 nl.mm-1. min-1 and hydraulic conductivity (Lp, cm.s-1.atm-1 X 10(7)) rose to 123 +/- 22. After 25 microunits/ml ADH in the presence of 3.75 mM calcium bath (n=7), Jv rose to 2.96 +/- 0.6 nl.mm-1.min-1 (P less than 0.05 vs. control) and Lp rose to 286 +/- 62 cm.s-1.atm-1 X 10(7) (P less than 0.02 vs. 1.25 mM bath calcium control). Tubules (n=6) perfused with 3.75 mM Ca and bathed in 3.75 mM Ca also showed an Lp of 279 +/- 82 cm.s-1.atm-1 X 10 (7) following 25 microunits/ml ADH. Tubules similarly studied in 1.25 (n=6) or 3.75 mM Ca (n=6) bath but treated with 10(-4) M 8-[p-chlorophenylthio]cAMP demonstrated Lp of 222 +/- 26 and 235 +/- 37 cm.s-1.atm-1 X 10(7), respectively. These data suggest that increased bath Ca enhances ADH- but not cAMP-stimulated water flow in the rabbit cortical collecting tubule. High perfusate Ca2+ does not alter the stimulatory effect of elevated peritubular Ca2+.

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