Alpha 1-adrenoceptors in parotid cells: age does not alter the ratio of alpha 1A and alpha 1B subtypes.
Epinephrine stimulation of 45Ca2+ efflux and inositol 1,4,5-trisphosphate ((1,4,5)IP3) production in parotid cell aggregates from mature rats was greatly inhibited (approximately 70%) by WB 4101 and 5-methylurapidil as compared to a small decrease by chloroethylclonidine (approximately 30%). The combination of WB 4101 or 5-methylurapidil and chloroethylclonidine completely blocked the action of epinephrine. The same relative inhibition was observed with senescent animals. The results suggest (1) that rat parotids contain both alpha 1-adrenoceptor subtypes, i.e., alpha 1A and alpha 1B, in an approximate functional ratio of 70:30, (2) that this relative ratio is not altered during aging, and (3) that both receptors partially mediate 45Ca2+ efflux and (1,4,5)IP3 production in this system.
Molecular Physiology and Genetics Section, NIA, NIH, Baltimore, MD 21224.
R
R
Villalobos-Molina
A
A
Miyamoto
M A
MA
Kowatch
G S
GS
Roth
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000375:Aging / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D003000:Clonidine / Q000031:analogs & derivatives / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D004837:Epinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D007293:Inosine Triphosphate / Q000378:metabolism; D008297:Male; D010306:Parotid Gland / Q000166:cytology / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D010879:Piperazines; D011942:Receptors, Adrenergic, alpha; D007293:Inosine Triphosphate; C057446:5-methylurapidil; C051731:chlorethylclonidine; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; D003000:Clonidine; D002118:Calcium; D004837:Epinephrine