In:
Frontiers in Physiology, Frontiers Media SA, Vol. 13 ( 2022-11-9)
Abstract:
Basolateral potassium channels in the distal convoluted tubule (DCT) are composed of inwardly-rectifying potassium channel 4.1 (Kir4.1) and Kir5.1. Kir4.1 interacts with Kir5.1 to form a 40 pS K + channel which is the only type K + channel expressed in the basolateral membrane of the DCT. Moreover, Kir4.1/Kir5.1 heterotetramer plays a key role in determining the expression and activity of thiazide-sensitive Na-Cl cotransport (NCC). In addition to Kir4.1/Kir5.1, Kir1.1 (ROMK) is expressed in the apical membrane of the late DCT (DCT2) and plays a key role in mediating epithelial Na + channel (ENaC)-dependent K + excretion. High dietary-K + -intake (HK) stimulates ROMK and inhibits Kir4.1/Kir5.1 in the DCT. Inhibition of Kir4.1/Kir5.1 is essential for HK-induced suppression of NCC whereas the stimulation of ROMK is important for increasing ENaC-dependent K + excretion during HK. We have now used the patch-clamp-technique to examine whether gender and Cl − content of K + -diet affect HK-induced inhibition of basolateral Kir4.1/Kir5.1 and HK-induced stimulation of ROMK. Single-channel-recording shows that basolateral 40 pS K + channel (Kir4.1/Kir5.1) activity of the DCT defined by NP o was 1.34 (1% KCl, normal K, NK), 0.95 (5% KCl) and 1.03 (5% K + -citrate) in male mice while it was 1.47, 1.02 and 1.05 in female mice. The whole-cell recording shows that Kir4.1/Kir5.1-mediated-K + current of the early-DCT (DCT1) was 1,170 pA (NK), 725 pA (5% KCl) and 700 pA (5% K + -citrate) in male mice whereas it was 1,125 pA, 674 pA and 700 pA in female mice. Moreover, K + -currents (I K ) reversal potential of DCT (an index of membrane potential) was -63 mV (NK), −49 mV (5% KCl) and −49 mV (5% K-citrate) in the male mice whereas it was -63 mV, −50 mV and −50 mV in female mice. Finally, TPNQ-sensitive whole-cell ROMK-currents in the DCT2 /initial-connecting tubule (CNT) were 910 pA (NK), 1,520 pA (5% KCl) and 1,540 pA (5% K + −citrate) in male mice whereas the ROMK-mediated K + currents were 1,005 pA, 1,590 pA and 1,570 pA in female mice. We conclude that the effect of HK intake on Kir4.1/Kir5.1 of the DCT and ROMK of DCT2/CNT is similar between male and female mice. Also, Cl − content in HK diets has no effect on HK-induced inhibition of Kir4.1/Kir5.1 of the DCT and HK-induced stimulation of ROMK in DCT2/CNT.
Type of Medium:
Online Resource
ISSN:
1664-042X
DOI:
10.3389/fphys.2022.1039029
Language:
Unknown
Publisher:
Frontiers Media SA
Publication Date:
2022
detail.hit.zdb_id:
2564217-0
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