Ca < sup > 2+ < /sup > -activated K < sup > + < /sup > channels modulate membrane potential in the human parathyroid cell: Possible role in exocytosis

Exp Cell Res. 2023 Nov 21:113858. doi: 10.1016/j.yexcr.2023.113858. Online ahead of print.ABSTRACTThe relationships between parathyroid hormone (PTH) secretion and parathyroid cell membrane potential, including the identities and roles of K+ channels that regulate and/or modulate membrane potential are not well defined. Here we have used Western blot/immunohistochemistry as well as patch-clamp and perifusion techniques to identify and localize specific K+ channels in parathyroid cells and to investigate their roles in the control of membrane potential and PTH secretion. We also re-investigated the relationship between membrane potential and exocytosis. We showed that in single human parathyroid cells K+ current is dependent on at least two types of Ca2+-activated K+ channels: a small-conductance Ca2+-activated K+ channel (KSK) and a large-conductance voltage and Ca2+-activated K+ channel (KBK). These channels were sensitive to specific peptide blocking toxins including apamin, charybdotoxin, and iberiotoxin. These channels confer sensitivity of the membrane potential in single cells to high extracellular K+, TEA, and peptide toxins. Blocking of KBK potently inhibited K+ channel current, and KBK was shown to be expressed in the plasma membrane of parathyroid cells. In addition, when using the capacitance technique as an indicator of exocytosis, clamping the parathyroid cell at -60 mV prevented exocytosis, whereas holding the membrane potential at 0 mV facilitated it. Taken tog...

Source: Experimental Cell Research - November 23, 2023 Category: Cytology Authors: Robert Br änström Vladana Vukojevi ć Ming Lu Ivan Shabo Hee-Chang Mun Arthur D Conigrave Lars-Ove Farnebo Catharina Larsson Source Type: research