Ca2+-dependence of 3H-catecholamines release evoked by black widow spider venom gland extract in rat hypothalamus, occipital cortex and caudate nucleus.
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.
D000818:Animals; D001180:Arthropod Venoms / Q000494:pharmacology*; D001740:Black Widow Spider; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism*; D002421:Caudate Nucleus / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism*; D004558:Electric Stimulation; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D011188:Potassium / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013111:Spider Venoms / Q000494:pharmacology*; D014316:Tritium / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology
D001180:Arthropod Venoms; D002395:Catecholamines; D013111:Spider Venoms; D014316:Tritium; D000001:Calcimycin; D014700:Verapamil; D011188:Potassium; D002118:Calcium