This study examined the effect of Gamma-Amino butyric acid (GABA) and selective GABA receptor related drugs on the electrically stimulated relaxation in the lower esophageal sphincter muscle (LES) of a cat. Tetrodotoxin $(10^{-6}\;M)$ suppressed the electrically stimulated (0.5-5 Hz) rela...
This study examined the effect of Gamma-Amino butyric acid (GABA) and selective GABA receptor related drugs on the electrically stimulated relaxation in the lower esophageal sphincter muscle (LES) of a cat. Tetrodotoxin $(10^{-6}\;M)$ suppressed the electrically stimulated (0.5-5 Hz) relaxation of the LES. However, guanethidine $(10^{-6}\;M)$ and atropine $(10^{-6}\;M)$ had no effect indicating that the relaxations were neurally mediated via the nonadrenergic and noncholinergic (NANC) pathways. NG-nitro-L-arginine methyl ester ($10^{-4}M$, L-NAME) also inhibited the relaxant response but did not completely abolish the electrically stimulated relaxation with 60% inhibition, which suggests the involvement of nitric oxide as an inhibitory transmitter. This study examined the role of GABA, an inhibitory neurotransmitter, on neurally mediated LES relaxation. GABA ($10^{-3}-10^{-5}M$, non selective receptor agonist), muscimol ($10^{-3}-10^{-5}M$, GABA-A agonist), and baclofen ($10^{-3}-10^{-5}M$, GABA-B agonist) had no significant effect on the electrically stimulated relaxation. Moreover, bicuculline ($10^{-5}M$, GABA-A antagonist) and phaclofen ($10^{-5}M$, GABA-B antagonist) had no inhibitory effect on the electrically stimulated relaxation. This suggests that GABA and the GABA receptor are not involved in the electrically stimulated NANC relaxation in the cat LES.
This study examined the effect of Gamma-Amino butyric acid (GABA) and selective GABA receptor related drugs on the electrically stimulated relaxation in the lower esophageal sphincter muscle (LES) of a cat. Tetrodotoxin $(10^{-6}\;M)$ suppressed the electrically stimulated (0.5-5 Hz) relaxation of the LES. However, guanethidine $(10^{-6}\;M)$ and atropine $(10^{-6}\;M)$ had no effect indicating that the relaxations were neurally mediated via the nonadrenergic and noncholinergic (NANC) pathways. NG-nitro-L-arginine methyl ester ($10^{-4}M$, L-NAME) also inhibited the relaxant response but did not completely abolish the electrically stimulated relaxation with 60% inhibition, which suggests the involvement of nitric oxide as an inhibitory transmitter. This study examined the role of GABA, an inhibitory neurotransmitter, on neurally mediated LES relaxation. GABA ($10^{-3}-10^{-5}M$, non selective receptor agonist), muscimol ($10^{-3}-10^{-5}M$, GABA-A agonist), and baclofen ($10^{-3}-10^{-5}M$, GABA-B agonist) had no significant effect on the electrically stimulated relaxation. Moreover, bicuculline ($10^{-5}M$, GABA-A antagonist) and phaclofen ($10^{-5}M$, GABA-B antagonist) had no inhibitory effect on the electrically stimulated relaxation. This suggests that GABA and the GABA receptor are not involved in the electrically stimulated NANC relaxation in the cat LES.
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문제 정의
This study examined the possibility that GABA might mediate LES relaxation. First, EFS-induced relaxation was investigated in an isolated LES of cats.
가설 설정
The response of the LES to various EFS frequencies. A: The LES musele strips were equilibrated for 2hrs in a warmed oxygenated Krebs solution prior to experimentation. The strips generated a tone at rest.
The strips generated a tone at rest. B: Original records of the frequency-response relationship for the EFS-induced relaxation of LES.
제안 방법
An analysis of variance was used to determine the statistical significance of the differences between the groups. If a significant difference was found, Duncan-s multiple range test was used to differentiate the differences between the ups.
Therefore, this study investigated the possibility of GABA involvement in the EFS-induced relaxation and in the modulation of the LES smooth muscle tone. In order to test whether or not GABA affects the basal tone of LES, the LES musale strips were exposed to exogenous GABA, GABA agonists or antagonists. However, none of these agents had any effect on the basal tone of the LES musale strips (data not shown).
(Kerr and Krantis, 1983). Therefore, this study investigated the possibility of GABA involvement in the EFS-induced relaxation and in the modulation of the LES smooth muscle tone. In order to test whether or not GABA affects the basal tone of LES, the LES musale strips were exposed to exogenous GABA, GABA agonists or antagonists.
대상 데이터
Adult cats of either gender weighing between 2.5 and 5 kg were used in this study. The cats were anesthetized with ketamine (50 mg/mL/kg).
데이터처리
An analysis of variance was used to determine the statistical significance of the differences between the groups. If a significant difference was found, Duncan-s multiple range test was used to differentiate the differences between the ups. A p value < 0.
성능/효과
This study investigated the characteristics of LES relaxation induced by EFS and examined the possibility that GABA may be a nonadrenergic and noncholinergic (NANC) neurotransmitter or that the GABA receptor pathway might be involved in the EFS-induced relaxation of LES.
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