Dryer, Stuart Evan the Effects of Adrenoceptor Agonists on Slow and Fast Synaptic Transmission in the Inferior Mesenteric Ganglion (img) of the Guinea Pig
ثبت نشده
چکیده
Literature pertaining to chemical neurotransmission the macroscopic and fine structure of the sympathetic nervous system, the pharmacology of alph^-adrenoceptors, and of synaptic transmission in sympathetic ganglia is re viewed. Catecholamines by preand postsynaptic mechanisms modulate fast neurotransmission in paravertebral ganglia. Opioids attenuate fast and slow neurotransmission in pre vertebral ganglia by presynaptic mechanisms. In this study pressure injection of adrenergic agonists attenuated fast, but not slow, excitatory postsynaptic potential (e.p.s.p.) amplitude. This effect was presynaptic; no effect was seen on direct stimulation, antidromic invasion, or anode break excitation. Postsynaptic effects were not temporally corre lated with reduced e.p.s.p. amplitude. The physiological and pharmacological significance is discussed.
منابع مشابه
Presence of prejunctional D2-dopaminoceptors and α2-adrenoceptors on the cholinergic nerve of the common bile duct of guinea pig
On most adrenergic and cholinergic nerve terminals, prejunctional α-adrenoceptors belonging to the α2-subtype have been identified. Activation of these receptors will decrease the release of norepinephrine. It has been reported that several isolated tissue preparations contain prejunctional dopamine receptors, the stimulation of which inhibits neurotransmission. It has remained uncertain whethe...
متن کاملColitis is associated with a loss of intestinofugal neurons.
Intestinofugal neurons sense and receive information regarding mechanical distension of the bowel and transmit this information to postganglionic sympathetic neurons in the prevertebral ganglia. Previous studies have demonstrated that trinitrobenzene sulfonic acid (TNBS)-induced colitis is associated with a loss of myenteric neurons that occurs within the first 12 h following the inflammatory i...
متن کاملAutonomic Nerve Regulation of Colonic Peristalsis in Guinea Pigs
BACKGROUND/AIMS Colonic peristalsis is mainly regulated via intrinsic neurons in guinea pigs. However, autonomic regulation of colonic motility is poorly understood. We explored a guinea pig model for the study of extrinsic nerve effects on the distal colon. METHODS Guinea pigs were sacrificed, their distal colons isolated, preserving pelvic nerves (PN) and inferior mesenteric ganglia (IMG), ...
متن کاملHydro-ethanolic Extract of Portulaca oleracea Affects Beta-adrenoceptors of Guinea Pig Tracheal Smooth Muscle
The stimulatory effect of the extract of Portulaca oleracea (P. olerace) on β-adrenoceptor of tracheal smooth muscle was examined. To examine β-adrenoceptor stimulatory effect, concentration response curve to isoprenaline was obtained in pre-contracted tracheal smooth muscle in the presence of three concentrations of aqueous-ethanolic extract, propranolol and saline. Values of EC50 (the effecti...
متن کاملHydro-ethanolic Extract of Portulaca oleracea Affects Beta-adrenoceptors of Guinea Pig Tracheal Smooth Muscle
The stimulatory effect of the extract of Portulaca oleracea (P. olerace) on β-adrenoceptor of tracheal smooth muscle was examined. To examine β-adrenoceptor stimulatory effect, concentration response curve to isoprenaline was obtained in pre-contracted tracheal smooth muscle in the presence of three concentrations of aqueous-ethanolic extract, propranolol and saline. Values of EC50 (the effecti...
متن کامل