Journal of Yeungnam Medical Science

Eun Mee Choi

3 Articles

Effect of Baclofen on the Cholinergic Nerve Stimulation in Isolated Rat Detrusor: Kwang Youn Lee, Keun Mi Lee, Eun Mee Choi, Hyoung Chul Choi, Jeoung Hee Ha, Won Joon Kim; Yeungnam Univ J Med. 1995;12(2):246-259. Published online December 31, 1995; DOI: https://doi.org/10.12701/yujm.1995.12.2.246

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Abstract PDF: This study aimed to investigate the mechanism of action of baclofen on the detrusor muscle isolated from rat. Rats (Sprague-Dawley) were sacrificed by decapitation and exsanguination. Horizontal muscle strips of 2 mm × 15 mm were prepared for isometric myography in isolated muscle chamber bubbled with 95% / 5%-OZ / CO2 at 371C, and the pH was maintained at 7.4. Detrusor strips contracted responding to the electrical field stimulation (EFS) by 2 Hz, 20 msec, monophasic square wave of 60 VDC. The initial peak of EFS-Induced contraction was tended to be suppresed by α,β-methylene-adenosine 5'-triphosphate (mATP), a partial agonist of purinergic receptor, and baclofen, a GABAB receptor agonist (statistically nonsignificant). The late sustained contraction by EFS was suppressed significantly (p<0.05) by additions of atropine, a cholinergic muscarinic receptor antagonist and baclofen. The adenosine 5'-triphosphate-induced contraction was completely abolished by mA TP but not by baclofen. In the presence of atropine, the subsequent addition of acetylcholine could not contract the muscle strips: but the addition of acetylcholine in the presence of baclofen evoked a contraction to a remarkable extent. These results suggest that in the condition of present study, the cholinergic innervation may play a more important role than the purinergic one, and baclofen suppresses the contractility of rat detrusor by the stimulation of the GABA receptors to inhibit the release of neurotransmitter from the cholinergic nerve ending

Characteristics of Potassium Channel in the Isolated Rat Detrusor Muscle.: Myeong Soo Jang, Eun Mee Choi, Jeoung Hee Ha, Kang Youn Lee, Won Joon Kim; Yeungnam Univ J Med. 1994;11(2):363-374. Published online December 31, 1994; DOI: https://doi.org/10.12701/yujm.1994.11.2.363

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Abstract PDF: The purpose of this study was to investigate the characteristics or the potassium channels existing in the rat urinary bladders. Smooth muscle strips of rat detrusor urinae were examined by isometric myography. Relaxation responses of detrusor muscle strips to the three potassium channel openers pinacidil, a cyanoguanidine derivative, BRL 38227, a benzopyran derivative and RP 52891, a tertrahydrothiopyran derivative were examined. The potassium channel openers reduced the basal tone, and the rank order of potency was RP 52891>pincidil>BRL 38227. Procaine, an inhibitor of the voltage-sensitive potassium channel tended to increase the basal tone, but it did not affect the relaxant effects of the calcium-activated potassium channel opener did not antagonize the relaxant effects, but it reduced the Emax of RP 52891 and BRL 38227. Glibenclamide, an inhibitor of the ATP-sensitive potassium channel, antagonized the relaxant effects of pinacidil, RP 52891 and BRL 38227 reducing the Emax of RP 52891 and BRl 38227. Galanin which inhibits secretion of insulin through opening the ATP-sensitive potassium channels in pancreatic β-cells rather increased the basal tone of the isolated detrusor strips. These results suggest that the urinary bladder of the rat has mainly the ATP-sensitive, glibenclamide sensitive potassium channel, which is a different type from that in the pancreatic β-islet cells.

Effect of GABA on the Contractility of Canine Trachealis Muscle.: Cheol Hoe Koo, Oh Chul Kwon, Eun Mee Choi, Kang Youn Lee, Won Joon Kim; Yeungnam Univ J Med. 1994;11(2):314-322. Published online December 31, 1994; DOI: https://doi.org/10.12701/yujm.1994.11.2.314

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Abstract PDF: This study aimed to investigate the existence of GABA receptor and the mechanisms of action of GABA and diazepam of the trachealis muscle isolated from dog. Horizontal muscle strips of 2mm×15mm were prepared from canine trachea, and isometric myography in isolated muscle chamber bubbled with 95/5%-O₂/CO₂ at 36℃, at the pH of 7.4 was performed. Muscle strips contracted responding to the electrical field stimulation (ESP) by 2~20 Hz, 20 msec, monophasic square wave of 60 VDC. GABA and diazepam suppressed the EFS-induced contractions to the similar extent, significantly. (p<0.05). Bicuculline, a GABA(A) receptor antagonist blocked both GABA- and diazepam-inhibitions; but DAVA, a GABA(B) receptor antagoinst did not affect either of them. These results suggest than in the canine trachealis muscle, there may be only GABA(A) receptor, and GABA and diazepam inhibit the contractility via GABA(A) receptor.

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