Faculty Collaboration Database

Estrogen receptors and effects of estrogen on membrane electrical properties of coronary vascular smooth muscle. J Cell Physiol 1979 Aug;100(2):375-82

Date

08/01/1979

Pubmed ID

511949

DOI

10.1002/jcp.1041000218

Scopus ID

2-s2.0-0018617333 (requires institutional sign-in at Scopus site)   173 Citations

Abstract

The effect of estrogen stimulation in vitro on the electrical properties of vascular smooth muscle (VSM), and the concentration of estrogen receptors in VSM were measured in isolated coronary arteries. Microelectrode measurements of the dog coronary artery membrane potential (Em) showed quiescent values of -51 millivolts (mV) and an input resistance (rin) of 10 megohms. Addition by diethylstilbestrol (DES) at 10(-6) M hyperpolarized the membrane to -64 mV and reduced input resistance (rin) to 5 megohms within 15 minutes. Extrapolation of the Em vs. log [K]o curve to zero potential gave similar values of [K]i of around 170 mM in both normal and DES treated muscles suggesting that the DES induced hyperpolarization is not due to increased Na-K pump activity. The 0.5% ethanol vehicle alone had no effect on the membrane potentials. Tetraethylammonium ion (TEA) induced action potentials in the previously quiescent tissue. When DES was applied in the presence of TEA, the membrane potential increased and the action potentials were abolished. Scatchard analysis of the estrogen receptor binding demonstrated both a high and a low affinity receptor for estrogen in the VSM. These data indicate that DES hyperpolarizes the VSM cells by a mechanism other than an increased Na-K pump activity. The mechanism of this increased Em may be due to factors which increase K+ conductance either mediated directly through estrogen interaction with its cytosolic receptors or through some unidentified second mechanism.

Author List

Harder DR, Coulson PB

Author

David Harder PhD, MS Emeritus Professor in the Physiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Action Potentials
Animals
Coronary Vessels
Diethylstilbestrol
Dogs
Electric Conductivity
Estrogens
Membrane Potentials
Muscle, Smooth, Vascular
Potassium
Receptors, Estrogen
Sodium