K+ release from rat parotid cells: an alpha 1-adrenergic mediated event.
To characterize alpha-adrenergic receptors in rat parotid gland tissue, 9,10-[9,10-3H(N)]-dihydro-alpha-ergocryptine ([3H]DHE) and [3H]prazosin binding to membranes and stimulated K+ release from parotid cell aggregates were examined. Prazosin (selective alpha 1-adrenergic antagonist), displacement of [3H]DHE binding from parotid membranes was biphasic, indicating the presence of both alpha 1- and alpha 2-adrenergic receptors. The numbers of alpha 1- and alpha 2-receptors were about equal. alpha 1-Adrenergic receptors were further studied by [3H]prazosin binding. [3H]Prazosin binding was a rapid, reversible, saturable and stereospecific process, with high affinity (KD = 0.38 nM) and low capacity (Bmax = 380 fmoles ligand bound/g tissue, 10.1 fmoles/mg protein) as determined by Scatchard analysis. The characteristics of [3H]prazosin binding were in good agreement with those of catecholamine-stimulated K+ release, suggesting that K+ release from rat parotid gland cells is an alpha 1-adrenergic mediated effect.
D000818:Animals; D002449:Cell Aggregation; D002462:Cell Membrane / Q000378:metabolism; D004088:Dihydroergotoxine / Q000378:metabolism; D008297:Male; D010306:Parotid Gland / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*
D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D004088:Dihydroergotoxine; D011188:Potassium; D011224:Prazosin