American journal of obstetrics and gynecology·1988
Area of Science:
Endocrinology
Cell Physiology
Background:
Parathyroid cells regulate calcium homeostasis.
Understanding their membrane potential is crucial for studying calcium signaling.
Purpose of the Study:
To investigate the relationship between extracellular calcium and the resting membrane potential of mouse parathyroid cells.
To explore the effects of calcium-like ions and potassium on parathyroid cell membrane potential.
Main Methods:
Intracellular microelectrode recordings were performed on mouse parathyroid cells in vitro.
The effects of varying extracellular calcium and potassium concentrations were analyzed.
Main Results:
The resting membrane potential of parathyroid cells is highly sensitive to extracellular calcium levels, exhibiting a sigmoid relationship.
Low extracellular calcium (1.5 mM) induced hyperpolarization (-50 mV), while normal calcium (2.5 mM) resulted in a less negative potential (-20 mV).
Magnesium, manganese, and lanthanum mimicked the hyperpolarizing effect of low calcium. Extracellular potassium significantly influenced membrane potential in low calcium but not in normal calcium conditions.
Conclusions:
The resting membrane potential of mouse parathyroid cells is primarily determined by extracellular calcium concentration.
Changes in extracellular calcium, particularly the transition to low calcium, alter the cell's electrical excitability and its dependence on extracellular potassium.