Differentiation by pyridoxal 5-phosphate, PPADS and IsoPPADS between responses mediated by UTP and those evoked by alpha, beta-methylene-ATP on rat sympathetic ganglia.
1. The effect of pyridoxal 5-phosphate, and the 2',4' and 2',5'-disulphonic acid isomers of 6-azophenylpyridoxal 5-phosphate (PPADS and IsoPPADS respectively) on depolarization of the rat superior cervical ganglion evoked by alpha, beta-methylene-adenosine 5'-triphosphate (alpha, beta-Me-ATP) and uridine 5'-triphosphate (UTP) were determined by a grease-gap recording technique. 2. Pyridoxal 5-phosphate (10-100 microM) and PPADS (10-100 microM) enhanced UTP- and depressed alpha, beta-Me-ATP-evoked depolarizations but did not significantly alter depolarizations evoked by potassium or hyperpolarizations evoked by adenosine. IsoPPADS (10 microM) depressed alpha, beta-Me-ATP-evoked depolarizations but did not alter depolarizations evoked by UTP. Depolarizations evoked by muscarine were depressed by IsoPPADS but not by pyridoxal 5-phosphate. 3. It is concluded that pyridoxal 5-phosphate, PPADS and IsoPPADS are antagonists at P2x-purinoceptors but not at the receptors that mediate UTP-evoked depolarization of the rat superior cervical ganglion. These observations substantiate the recent proposal that the rat superior cervical ganglia possess distinct receptors for purine and pyrimidine 5'-nucleotides, i.c. P2x-purinoceptors and pyrimidinoceptors respectively.
Connolly
G P
GP
Department of Physiology, University College London.
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002572:Cervical Plexus / Q000187:drug effects / Q000378:metabolism; D005728:Ganglia, Sympathetic / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D058914:Purinergic Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013237:Stereoisomerism; D014544:Uridine Triphosphate / Q000494:pharmacology
D058914:Purinergic Antagonists; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D014544:Uridine Triphosphate