Investigation of dopamine content, synthesis, and release in the rabbit retina in vitro: II. Effects of high potassium, adenylate cyclase activators, and N-n-propyl-3-(3-hydroxyphenyl) piperidine.
The modulation of 3,4-dihydroxyphenylethylamine (dopamine, DA) synthesis and release in rabbit retina in vitro by high K+; adenylate cyclase activators such as forskolin, 2-chloroadenosine, vasoactive intestinal polypeptide (VIP); and the putative DA autoreceptor agonist N-n-propyl-3-(3-hydroxyphenyl) piperidine (3-PPP) has been investigated. Incubation of retinas in 50 mM K+ resulted in the activation of tyrosine hydroxylase (TH). Activation did not require the presence of extracellular Ca2+. K+ 50 mM also induced a Ca2+-dependent release of DA. Forskolin 50 microM stimulated TH but 100 microM 2-chloroadenosine and 650 nM VIP did not. Individually, (+)-3-PPP, (-)-3-PPP, and (+/-)-3-PPP reduced DA synthesis and increased its release. The effects of (+/-)-3-PPP were dose-dependent and did not require the presence of extracellular Ca2+. The activation of TH induced by 50 mM K+, but not that induced by 50 microM forskolin, was abolished by 100 microM (+/-)-3-PPP.
D015762:2-Chloroadenosine; D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D008297:Male; D010880:Piperidines / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D012160:Retina / Q000187:drug effects / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
D010880:Piperidines; D015762:2-Chloroadenosine; D005576:Colforsin; D014660:Vasoactive Intestinal Peptide; C026539:preclamol; D014446:Tyrosine 3-Monooxygenase; D000262:Adenylyl Cyclases; D000241:Adenosine; D011188:Potassium; D002118:Calcium; D004298:Dopamine