• Title/Summary/Keyword: Biophysics

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DAMGO, a ${\mu}-Opioid$ Agonist and Cholecystokinin-Octapeptide Have Dual Modulatory Effects on Capsaicin-Activated Current in Rat Dorsal Root Ganglion Neurons

  • Eun, Su-Yong;Kim, Ji-Mok;Lee, Ji-Hye;Jung, Sung-Jun;Park, Joo-Min;Park, Yun-Kyung;Kim, Dong-Kwan;Kim, Sang-Jeong;Kwak, Ji-Yeon;Kim, Jun
    • The Korean Journal of Physiology and Pharmacology
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    • v.5 no.1
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    • pp.71-78
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    • 2001

  • Capsaicin, a pungent ingredient of hot pepper, elicits an intense burning pain when applied cutaneously and intradermally. Activation of capsaicin-gated channel in C-type dorsal root ganglion (DRG) neurons produces nonselective cationic currents. Although electrophysiological and biochemical properties of capsaicin-activated current $(I_{CAP})$ were studied, the regulatory mechanism and intracellular signaling pathway are still unclear. In the present study, we investigated the modulations of $I_{CAP}$ by DAMGO $({\mu}-opioid\;agonist)$ and cholecystokinin octapeptide (CCK-8). In 18 out of 86 cells, the amplitude of $I_{CAP}$ was significantly increased by DAMGO and completely reversed after washout, while $I_{CAP}$ was decreased by DAMGO in 25 cells. In 43 cells, DAMGO had no effect on $I_{CAP}$. Mean action potential duration was significantly different between 'increased-by-DAMGO' group and 'decreased-by-DAMGO' group. Mean amplitudes of $I_H$ were not significantly different between both groups. CCK-8 reversibly enhanced the amplitude of $I_{CAP}$ (5/13). DAMGO also increased $I_{CAP}$ amplitude significantly in the same cells. The amplitude of $I_{CAP}$ was increased in additive manner by combined applications of DAMGO and CCK-8 in these cells. These results suggest that DAMGO and CCK-8 can either increase or decrease $I_{CAP}$ presumably depending on the subtypes of DRG cells and classified by electrophysiological properties.

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Effects of Chlorhexidine digluconate on Rotational Rate of n-(9-Anthroyloxy)stearic acid in Model Membranes of Total Lipids Extracted from Porphyromonas gingivalis Outer Membranes

  • Jang, Hye-Ock;Kim, Dong-Won;Kim, Byeong-Ill;Sim, Hong-Gu;Lee, Young-Ho;Lee, Jong-Hwa;Bae, Jung-Ha;Bae, Moon-Kyoung;Kwon, Tae-Hyuk;Yun, Il
    • The Korean Journal of Physiology and Pharmacology
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    • v.8 no.2
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    • pp.83-88
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    • 2004

  • The purpose of this study was to provide a basis for studying the molecular mechanism of pharmacological action of chlorhexidine digluconate. Large unilamellar vesicles (OPGTL) were prepared with total lipids extracted from cultured Porphyromonas gingivalis outer membranes (OPG). The anthroyloxy probes were located at a graded series of depths inside a membrane, depending on its substitution position (n) in the aliphatic chain. Fluorescence polarization of n-(9-anthroyloxy)stearic acid was used to examine effects of chlorhexidine digluconate on differential rotational mobility, while changing the probes' substitution position (n) in the membrane phospholipids aliphatic chain. Magnitude of the rotational mobility of the intact six membrane components differed depending on the substitution position in the descending order of 16-(9-anthroyloxy)palmitic acid (16-AP), 12, 9, 6, 3 and 2-(9-anthroyloxy)stearic acid (12-AS, 9-AS, 6-AS, 3-AS and 2-AS). Chlorhexidine digluconate increased in a dose-dependent manner the rate of rotational mobility of hydrocarbon interior of the OPGTL prepared with total lipids extracted from cultured OPG, but decreased the mobility of membrane interface of the OPGTL. Disordering or ordering effects of chlorhexidine digluconate on membrane lipids may be responsible for some, but not all of its bacteriostatic and bactericidal actions.

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