BIPHASIC MODULATION OF POTASSIUM RELEASE IN RAT PAROTID-GLAND BY CARBACHOL AND PHENYLEPHRINE

Abstract

Both 86Rb and 42K appeared to serve as useful markers for K movements in rat parotid gland slices. Carbachol and phenylephrine elicited a biphasic increase in K release (86Rb release) that was dose related and could be blocked by atropine and phentolamine, respectively. The early transient phase of 86Rb release lasted from 3-6 min and was not blocked by removal of external Ca. The transient phase probably corresponded to the transient hyperpolarization seen by others in response to .alpha. adrenergic or cholinergic agents. The latter sustained phase of 86Rb release was qualitatively blocked by chelation of external Ca ions or by 1 mM LaCl3. Thus, the sustained phase of release appeared to relate to the loss of total K seen by others with this tissue and to the mechanisms responsible for transporting water from blood to saliva.