Beta-adrenoceptors modulate noradrenaline release from axonal sprouts in cultured rat superior cervical ganglia.
Superior cervical ganglia of rats grown in organ culture were used to study the effect of beta-receptor stimulants and antagonists on 3H-noradrenaline release in response to stimulation by KC1 (75 mM). (--)-Isoprenaline 1X 10(-9)--1 X 10(-7) M) increased 20--25% the release of 3H-noradrenaline from cultured ganglia exposed to KC1. Isoprenaline did not modify either the spontaneous (non-calcium dependent) release of 3H-noradrenaline from cultured ganglia, or the KC1-stimulated release from fresh ganglia. The effect of (--)-isoprenaline was blocked by (--)-propranolol 5 X 10(-9) -- 1 X 10(-8) M and by butoxamine 10(-6) M, but not by (+)-propranolol (1 -- 5 X 10(-8) M), practolol (1 X 10(-8) -- 1 X 10(-6) M), or sotalol (1 X 10(-7) -- 1 X 10(-6) M). Isoprenaline induced augmentation of 3H-noradrenaline release and its antagonism by (--)-propranolol still occurred in the presence of DMI. It is suggested that presynaptic beta-receptors in sympathetic nerve terminals may be involved in a positive feedback of noradrenaline release.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001369:Axons / Q000378:metabolism*; D003891:Desipramine / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000378:metabolism* / Q000648:ultrastructure; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009411:Nerve Endings / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D009924:Organ Culture Techniques; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011941:Receptors, Adrenergic / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000502:physiology*
D000319:Adrenergic beta-Antagonists; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D011189:Potassium Chloride; D007545:Isoproterenol; D003891:Desipramine; D009638:Norepinephrine