ABSTRACT
The release of 3H-catecholamines evoked by Black Widow spider venom gland extract (BW-GE) has been studied in the isolated rat hypothalamus (HT), occipital cortex (OC), preloaded with 3H-noradrenaline, and isolated caudate nucleus (CN) preloaded with 3H-dopamine. The BWGE at a concentration of 0.04 gland/ml increased significantly 3H-output in isolated slices of rat HT, OC and CN. This effect was markedly depressed when control calcium concentration in the medium (1.68 mM) was reduced (0-0.56 mM) or enhanced (3 mM), as well as in the presence of an organic Ca2+ antagonist, verapamil (10 microM), or ionophore A 23187 (40 microM), a substance that increases the influx of calcium into the cell. Morphine (up to 0.4 mM) evoked no effect upon 3H-noradrenaline release induced by BWGE. Morphine (10 microM), 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. Our results demonstrate differences between BWGE and potassium stimuli, and indicate that BWGE releases 3H-catecholamines by a calcium dependent process.
Subject(s)
Arthropod Venoms/pharmacology , Calcium/metabolism , Catecholamines/metabolism , Caudate Nucleus/metabolism , Cerebral Cortex/metabolism , Hypothalamus/metabolism , Spider Venoms/pharmacology , Animals , Black Widow Spider , Calcimycin/pharmacology , Electric Stimulation , Male , Potassium/metabolism , Rats , Rats, Inbred Strains , Tritium/metabolism , Verapamil/pharmacologySubject(s)
Male , Animals , Rats , Calcium , Catecholamines , Caudate Nucleus , Cerebral Cortex , Hypothalamus , Spider VenomsSubject(s)
Male , Animals , Rats , Calcium , Catecholamines , Cerebral Cortex , Hypothalamus , Caudate Nucleus , Spider VenomsABSTRACT
The release of 3H-catecholamines evoked by Black Widow spider venom gland extract (BW-GE) has been studied in the isolated rat hypothalamus (HT), occipital cortex (OC), preloaded with 3H-noradrenaline, and isolated caudate nucleus (CN) preloaded with 3H-dopamine. The BWGE at a concentration of 0.04 gland/ml increased significantly 3H-output in isolated slices of rat HT, OC and CN. This effect was markedly depressed when control calcium concentration in the medium (1.68 mM) was reduced (0-0.56 mM) or enhanced (3 mM), as well as in the presence of an organic Ca2+ antagonist, verapamil (10 microM), or ionophore A 23187 (40 microM), a substance that increases the influx of calcium into the cell. Morphine (up to 0.4 mM) evoked no effect upon 3H-noradrenaline release induced by BWGE. Morphine (10 microM), 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. Our results demonstrate differences between BWGE and potassium stimuli, and indicate that BWGE releases 3H-catecholamines by a calcium dependent process.