Influence of Pentobarbital-Na on Stimulation-Evoked Catecholamine Secretion in The Perfused Rat Adrenal Gland

Abstract

ObjectivesThe present study was attempted to investigate the effects of pentobarbital-Na, one of the barbiturates which are known to depress excitatory synaptic transmission in the central nervous system at concentrations similar to those required for the induction and maintenance of anesthesia, on catecholamines (CA) secretion evoked by cholinergic stimulation and membrane-depolarization from the isolated perfused rat adrenal gland, and to clarify the mechanism of its action.MethodsMature male Sprague-Dawley rats were anesthetized with thiopenal-Na(40mg/kg, s.c.). The adrenal gland was isolated by the methods of Wakade. A cannula used for perfusion of the adrenal gland was inserted into the distal end of the renal vein. The adrenal gland was carefully removed from the animal and placed on a platform of a leucite chamber.ResultsThe perfusion of pentobarbital-Na(30–300uM) into an adrenal vein for 20 min produced relatively dose-dependent inhibition in CA secretion evoked by ACh(5.32mM) DMPP(100uM for 1 min), McN-A-343(200uM for 2 min), Bay-K-8644(10uM) and high potassium(56mM), while it did not affect the CA secretion of cyclopiazonic acid(10uM). Also, in the presence of thiopental-Na (100uM), CA secretory responses evoked by ACh, DMPP, McN-A-343 and high K+ were markedly depressed. Moreover, in adrenal glands preloaded with ketamine(100uM for 20 min), which is known to be a dissociative anesthetic, CA secretion evoked by ACh, DMPP, McN-A-343 and high K+ were significantly attenuated.ConclusionTaken together, these experimental results suggest that pentobarbital-Na depresses CA release evoked by both cholinergic stimulation and membrane-depolarization from the isolated rat adrenal medulla and that this inhibitory activity may be due to the result of the direct inhibiton of Ca++ influx into the chromaffin cells without any effect on the calcium mobilization from the intracellular store.

Detection of thiopental in the steroid fraction of serum from neonates following maternal exposure

“…In rats, thiopental (10 M-1 mM) has been shown to affect pulmonary surfactant protein RNA content, aorta nitric oxide production, adrenomedullin synthesis in smooth muscle cells, and release of adrenal catecholamines [4][5][6][7]. In the present study, the concentrations of thiopental in both cord and neonatal serum samples varied, but were estimated to be less than 10 M. These concentrations are thus below the concentrations of thiopental used in those animal studies.…”

Intravenously administered hypocretin-1 alters brain amino acid release: an in vivo microdialysis study in rats

“…It is possible that an indirect effect through peripheral pathways might trigger glutamate release, although barbiturate anaesthesia has an inhibitory effect on many peripheral pathways (Matsukawa et al . 1993; Lim et al . 1997).…”

“…Therefore, in the current study we monitored the effects of Hcrt administration in anaesthetized rats to eliminate the possibility of motor mediation, and to prevent other effects that are inhibited by barbiturate anaesthesia (Matsukawa et al . 1993; Lim et al . 1997).…”

Intravenously administered hypocretin-1 alters brain amino acid release: an in vivo microdialysis study in rats

“…We have also reported that motor activation produces a marked increase in Hcrt release (Kiyashchenko et al 2002;Wu et al 2002). Therefore, in the current study we monitored the effects of Hcrt administration in anaesthetized rats to eliminate the possibility of motor mediation, and to prevent other effects that are inhibited by barbiturate anaesthesia (Matsukawa et al 1993;Lim et al 1997). Hcrt-1 crosses the blood-brain barrier by diffusion (Kastin & Akerstrom, 1999).…”