Journal of Neurophysiology, Vol 61, Issue 5 1036-1052, Copyright © 1989 by APS
5 alpha-dihydrotestosterone has nonspecific effects on membrane channels and possible genomic effects on ACh-activated channels
S. D. Erulkar and D. M. Wetzel
Department of Pharmacology, University of Pennsylvania Medical School, Philadelphia 19104.
1. Myotubes cultured from adult male Xenopus laevis laryngeal muscle have
been found to express androgen receptors. 2. Using patch-clamp techniques,
it was found that 5 alpha-dihydrotestosterone (5 alpha-DHT) can act
directly at membranes of these myotubes to alter the kinetic properties of
acetylcholine- (ACh) activated single channels. 3. When the culture medium
contains 5 alpha-DHT for greater than 6 days, the androgen acts through its
receptors to markedly increase ACh-activated, single-channel conductances
and alter single-channel kinetics. These effects do not occur if the
antiandrogen, flutamide, which prevents the androgen from combining with
its receptor, is added to the medium before the addition of the 5
alpha-DHT. These effects also do not occur in myotubes cultured from
quadriceps femoris muscles that have much lower levels of specific androgen
receptor. 4. When alpha-bungarotoxin (alpha-BTX) is added to the medium for
3 h before recording, no ACh channels can be recorded from myotubes in
control medium within 5 h after washout of the alpha-BTX. However, when the
culture medium contains 5 alpha-DHT for greater than or equal to 6 days,
ACh channels can be recorded within 8 min of the washout of the alpha-BTX.
5. The results suggest that 5 alpha-DHT may act to alter the properties of
ACh-activated ion channels at multiple sites in excitable cells.
