NORADRENALINE RELEASE FROM RAT SYMPATHETIC NEURONS EVOKED BY P-2-PURINOCEPTOR ACTIVATION

Authors
Citation
S. Boehm, NORADRENALINE RELEASE FROM RAT SYMPATHETIC NEURONS EVOKED BY P-2-PURINOCEPTOR ACTIVATION, Naunyn-Schmiedeberg's archives of pharmacology, 350(5), 1994, pp. 454-458
Citations number
36
Categorie Soggetti
Pharmacology & Pharmacy
ISSN journal
00281298
Volume
350
Issue
5
Year of publication
1994
Pages
454 - 458
Database
ISI
SICI code
0028-1298(1994)350:5<454:NRFRSN>2.0.ZU;2-Y
Abstract
The effects of ATP and analogues on the release of previously incorpor ated H-3-noradrenaline were studied in cultured sympathetic neurons de rived from superior cervical ganglia of neonatal rats. Electrical fiel d stimulation (40 mA at 3 Hz) of the neurons for 10 s markedly enhance d the outflow of tritium. ATP applied for 5 s to 2 min at concentratio ns of 0.01 to 1 mmol/l caused a time- and concentration-dependent over flow with half maximal effects at about 10 s and 100 mu mol/l, respect ively. 2-Methylthio-ATP was equipotent to ATP in inducing H-3-overflow ADP (100 mu mol/l), when applied for 2 min, also caused a small H-3-o verflow, but alpha, beta- methylene-ATP (100 mu mol/l), AMP (100 mu mo l/l), R(-)N-6-(2-phenylsiopropyl)-adenosine (R(-)-PIA; 10 mu mol/l) an d 5'-N-ethylcarboxamidoadenosine (NECA; 1 mu mol/l) did not. The H-3-o verflow induced by 10 s applications of 100 mu mol/l ATP was abolished by suramin (100 mu mol/l) and reduced by about 70% by reactive blue 2 (3 mu mol/l). Electrically evoked overflow in contrast, was slightly enhanced by suramin, but not modified by reactive blue 2. Xanthine ami ne congener (10 mu mol/l) and hexamethonium (10 mu mol/l) did not alte r ATP-evoked release. Removal of extracellular Ca2+ from the medium re duced ATP- and electrically induced overflow by about 95%. Tetrodotoxi n (1 mu mol/l) abolished electrically evoked H-3-overflow but inhibite d ATP-induced overflow by only 70%. The alpha(2)-adrenoceptor agonist UK 14,304 at a concentration of 1 mu mol/l diminished both electricall y and ATP-evoked tritium overflow by approximately 70%. These results indicate that activation of P-2-purinoceptors stimulates noradrenaline release from rat sympathetic neurons. The release resembles electrica lly induced transmitter release, but additional mechanisms may contrib ute.