AUTONOMIC BLOCKING PROPERTIES OF HEMICHOLINIUM (HC-3)

¹ Department of Pharmacology, College of Medicine, State University of Iowa, Iowa City, Iowa

HC-3 was effective in blocking the vagal innervation to the colon of rabbits and hypogastric innervation to the bladder, but it did not decrease the irritability and spontaneous movements of these organs. HC-3 was effective in inhibiting the pelvic nerve innervation to the bladder only when higher frequencies of stimulation were used and the time required for onset of inhibition was related to the frequency of stimulation. Evidence was presented that HC-3 did not block the receptors at the postganglionic parasympathetic sites. Exogenous choline partially antagonized the blocking actions of HC-3 at all sites.