AJP - Cell Physiology, Vol 235, Issue 5 204-C211, Copyright © 1978 by American Physiological Society
Sensitivity of excitable and inexcitable membranes to alpha-dihydrograyanotoxin II
J. G. Starkus and T. Narahashi
A variety of excitable and inexcitable preparations have been examined for
their sensitivity to the depolarizing action of alpha-dihydrograyanotoxin
II. alpha-Dihydrograyanotoxin II was effective in producing membrane
depolarization in giant axons from the crayfish (Procambarus clarki) and
sartorius muscle fibers from the frog (Rana pipiens) and the salamander
(Taricha torosa). The toxin-induced depolarization was reversed by lowering
the external sodium concentration. High concentrations of tetrodotoxin and
saxitoxin were also effective in reversing the depolarization in the
various grayanotoxin-sensitive preparations studied except in the
salamander sartorius muscle, in which sodium-dependent action potentials
were highly resistant to tetrodotoxin and saxitoxin. In contrast,
alpha-dihydrograyanotoxin II was ineffective in changing the resting
membrane potential in the muscle fibers of the crayfish (Procambarus clarki
and Orconectes virilis) and in the salivary gland giant cells from
Drosophila virilis. Of the preparations that were examined, only the
membranes that produce a sodium-dependent action potential are sensitive to
the depolarizing action of alpha-dihydrograyanotoxin II.
