AJP - Gastrointestinal and Liver Physiology, Vol 245, Issue 6 780-G785, Copyright © 1983 by American Physiological Society
Dantrolene and basal ileal sodium and chloride transport: involvement of calcium stores
M. Donowitz, S. Cusolito, L. Battisti and G. W. Sharp
The effect of dantrolene on active ion transport in rabbit ileum was
determined using the Ussing chamber short-circuiting technique. Dantrolene
prevents the release of calcium from intracellular stores in skeletal
muscle and was used to probe the role of intracellular calcium stores in
intestinal ion transport. A saturated solution of dantrolene (approx 25
microM) decreased ileal short-circuit current and potential difference,
increased conductance and mucosal-to-serosal and net Na and Cl fluxes, but
did not alter serosal-to-mucosal Na and Cl fluxes. The dantrolene
stimulation of active Na and Cl absorption was specific since it did not
alter glucose-dependent Na absorption, transport changes caused by Ca2+
ionophore A23187, or the increase in short-circuit current caused by
dibutyryl cAMP or theophylline. These effects were associated with an
increase in total ileal calcium content and a decreased rate of 45Ca2+
efflux without any change in 45Ca2+ influx from the serosal or mucosal
surfaces. These findings are consistent with an effect of dantrolene to
stimulate active ileal Na and Cl absorption by a mechanism involving
lowered cytosol Ca2+ levels and compatible with trapping calcium in
intracellular stores. It thus appears as if intracellular calcium stores
have an important role in the control of basal ion transport in the
intestine.
