Paper Information

Title: 

INHIBITION OF THE NITRERGIC RELAXATION OF RAT ANOCOCCYGEUS MUSCLE BY LITHIUM

Type: POSTER
Author(s): KARIM ELAH A.R.*,GHASEMI MAHDI,GHAHRAMANI MOHAMMAD HOSSEIN,DEHPOUR A.R.
 
 *DEPARTMENT OF PHARMACOLOGY, SCHOOL OF MEDICINE, YAZD, IRAN
 
Name of Seminar: IRANIAN CONGRESS OF PHYSIOLOGY AND PHARMACOLOGY
Type of Seminar:  CONGRESS
Sponsor:  PHYSIOLOGY AND PHARMACOLOGY SOCIETY, MASHHAD UNIVERSITY OF MEDICAL SCIENCE
Date:  2009Volume 19
 
 
Abstract: 

Despite long term uses of lithium for the treatment of manic-depressive illness, any definitive mechanism for the effects of lithium has been established. Some studies have suggested that nitric oxide may be involved in some of lithium-induced responses. The rat anococcygeus muscle is one of the first tissues that nitrergic nerve was found in it. Since detection of nitric oxide as a neurotransmitter in nitrergic nerves anococcygeus muscle became a useful model to investigate nitrergic relaxation in the non-vascular smooth muscle. The isolated precontracted (phenylephrine,7.5μm) rat anococcygeus muscle were relaxed via electrical field stimulation (5 Hz) in the absence or presence of lithium or in tissues excised from ex vivo lithium-treated animals (600 mg/l in drinking water for 30 days). Effects of L-NAME (0.03 and 100 μM), ODQ (1 μM) and L-arginine (1 mM) on relaxations and nNOS gene expression of rat anococcygeus muscle were investigated. Data showed that both acute and chronic lithium administration caused a significant decrease in nitergic relaxation of rat anococcygeus muscle. Low concentration of lithium administered in combination with non-effective concentration of LNAME showed a strong inhibitory effect on the neurogenic relaxation of rat anococcygeus muscle. L-arginine, in noneffective concentration, reversed the inhibition of relaxant responses to EFS induced by lithium. This study for the first time showed that nNOS expression was enhanced in anococcygeus muscles isolated from lithium-treated rats. Our finding approved that the L-arginine/NO pathway may be involved in the lithium-induced impairment in theneurogenic relaxation of rat anococcygeus muscle.

 
Keyword(s): LITHIUM, NITRERGIC RELAXATION, NITRIC OXIDE, ANOCOCCYGEUS MUSCLE, RAT
 
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