CA-2+-DEPENDENCE OF H-3-LABELED CATECHOLAMINES RELEASE EVOKED BY BLACK-WIDOW SPIDER VENOM GLAND EXTRACT IN RAT HYPOTHALAMUS, OCCIPITAL CORTEX AND CAUDATE-NUCLEUS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 33  (4) , 293-298
Abstract
The release of 3H-catecholamines evoked by black widow spider venom gland extract (BW-GE) was studied in the isolated rat hypothalamus (HT), occipital cortex (OC), preloaded with 3H-noradrenaline [norepinephrine] and isolated caudate nucleus (CN) preloaded with 3H-dopamine. The BWGE at 0.04 gland/ml increased significantly 3H-output in isolated slices of rat HT, OC and CN. This effect was markedly depressed when control Ca concentration in the medium (1.68 mM) was reduced (0-0.56 mM) or enhanced (3 mM), and in the presence of an organic Ca2+ antagonist, verapamil (10 .mu.M), or ionophore A 23187 (40 .mu.M), a substance that increased the influx of Ca into the cell. Morphine (up to 0.4 mM) evoked no effect upon 3H-noradrenaline release induced by BWGE. Morphine (10 .mu.M), but not ionophore A 23187 or high Ca2+ (3 mM), reduced 3H-noradrenaline release induced by 20 mM K+. Low Ca2+ and verapamil produced similar effects than those observed for BWGE. Results demonstrated differences between BWGE and K+ stimuli, and indicated that BWGE released 3H-catecholamines by a Ca dependent process.