Peroxidase secretion from rat lacrimal gland cells in vitro. I. Alpha-adrenergic stimulation in the absence of alpha-adrenoceptors.
The identification of alpha-adrenergic receptors and subdivision into alpha 1- or alpha 2-subtypes were studied by measuring the specific binding of the radioligands [3H]-prazosin as well as [3H]-clonidine to membranes prepared from homogenized rat lacrimal glands. The absence of high-affinity binding for [3H]-prazosin as well as for [3H]-clonidine indicates that rat lacrimal glands do not possess a substantial amount of alpha 1- and alpha 2-adrenoceptors. The binding data correspond with the characterization by pharmacological means. Monolayers of lacrimocytes were incubated with various selective alpha 1-, alpha 2-, beta-adrenergic agonists and antagonists or other substances, and peroxidase discharge was measured over a period of 1 hr. Among various substances only L-norepinephrine, L-phenylephrine, tyramine and ionophore A 23187 were stimulants of peroxidase secretion, whereas the adrenergic-stimulated secretory response was only suppressed by phentolamine.
D000818:Animals; D003000:Clonidine / Q000378:metabolism; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000378:metabolism*; D007765:Lacrimal Apparatus / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D009195:Peroxidase; D010544:Peroxidases / Q000378:metabolism*; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000378:metabolism*; D013268:Stimulation, Chemical; D013565:Sympatholytics / Q000494:pharmacology; D013566:Sympathomimetics / Q000494:pharmacology
D007527:Isoenzymes; D011942:Receptors, Adrenergic, alpha; D013565:Sympatholytics; D013566:Sympathomimetics; D010544:Peroxidases; D009195:Peroxidase; D003000:Clonidine; D011224:Prazosin