Key result
A 175-pS potassium-selective channel in bovine parathyroid cells closes when internal calcium increases above 160 nM, potentially explaining cell depolarization in high-calcium solutions.
Identification of a unique calcium-activated potassium channel in bovine parathyroid cells that closes at high internal calcium concentrations, explaining their depolarization in high-calcium solutions.
Does not yet alter hyperparathyroidism management; leaves open the channel's role in human calcium sensing.
Parathyroid cells have unusual responses to an increase in the external calcium concentration--a reduction in secretion and a depolarization. In an attempt to explain this behavior, we have studied voltage-clamped inside-out patches from bovine parathyroid cells. We found a potassium-selective channel that requires internal calcium to open and has a 175-pS conductance. This channel differs from calcium-activated potassium channels that have been found in other cells in that it closes when the internal calcium concentration is increased above about 160 nM. This channel can account for the depolarization that occurs in parathyroid cells in high-calcium solutions. It may also account for the reduced secretion in high-calcium solutions.
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Jia et al. (1988) studied None (in vitro bovine parathyroid cells). Internal calcium concentration was evaluated on Channel open probability. A 175-pS potassium-selective channel in bovine parathyroid cells closes when internal calcium increases above 160 nM, potentially explaining cell depolarization in high-calcium solutions.
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