Role of calcium in the fade of the potassium release response in the rat parotid gland.

Publisher Website
Google Scholar
Abstract
The 86Rb release response in the parotid due to .alpha.-adrenergic (epinephrine), muscarinic (carbachol) or peptide (Substance P) receptor activation exhibited fade, a return of efflux to control levels despite the continuing presence of agonist. The time course of fade of the response to all 3 agonists was independent of the concentration of the agonist. After fade was fully developed to 1 agonist, the response to an agonist acting on a different receptor was either absent or greatly diminished. Removal of carbachol from muscarinic receptors with atropine 10 min prior to Substance P partially restored the ability of Substance P to produce a response. Fade of the response with all 3 agonists was greatly retarded by the omission of Ca. Release of .alpha.-amylase did not appear to fade following exposure to carbachol or Substance P. The K+ release response may be inactivated with time due to diminution in responsiveness of the K+ channel to an increase in internal Ca2+.