Electrical activity in chromaffin cells of intact XXXX adrenal gland.

@entity19 @entity5128 @entity4780 @entity1022 @entity1617 @entity8594 @entity3897 @entity2899 @entity934
Membrane potentials of medullary chromaffin cells of the adrenal gland of the @entity19 were measured in situ. Resting potential (-54.3 +/- 8.8 mV) depended on extracellular [K+] as predicted by the constant-field equation with a permeability ratio, PNa/PK, of 0.09. Current-voltage (I-V) relationships showed that the current is rectified across the chromaffin cell membrane. A rectification ratio of 0.4 was calculated from the slopes of the I-V curves for positive (41 +/- 26 @entity4780 ) and negative (103 +/- @entity4780 ) currents. Because input resistance for a resting chromaffin cell in isolation is approximately 5 G omega, the chromaffin cells in situ behave as if they were electrically coupled. Most cells responded to depolarizing current pulses with repetitive action potentials, but only 50% of them showed spontaneous electrical activity. Spontaneous activity was often seen in the presence of @entity1022 (3 microM). Although the application of the K+-channel blockers @entity5128 and @entity8594 greatly increased the amplitude of the action potentials, only @entity8594 induced continuous electrical activity. Application of @entity934 ( @entity1617 ) always depolarized the cell membrane. This effect was blocked by @entity3897 but not by @entity2899 , suggesting that ACh stimulation of chromaffin cells in the @entity19 involves activation of muscarinic receptors.
