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Biomedical subjects

B S Kang

Publications and source records attributed to B S Kang.

49 records · Page 3Linked to original sources
PubMed1992

Effects of vanadate on vascular contractility and membrane potential in the rabbit aorta.

Isolated rabbit aortic ring with intact endothelial cell preparations precontracted with NE (10(-7) M) were relaxed by vanadate in a dose dependent manner (from 0.2 to 2 mM). Application of vanadate and ACh during the tonic phase of high K+(100 mM)-induced contraction showed a slight relaxation in contrast to that in NE-induced contraction, but sodium nitroprusside (10 microM) more effectively relaxed the aortic ring preparations in high K+ contraction than that of vanadate. Vanadate-induced relaxation in NE-contracted aortic rings was reversed by application of BaCl2 (50 microM) or glibenclamide (10 microM). Furthermore, Vanadate hyperpolarized membrane potential of smooth muscle cells in endothelium-intact aortic strips and this effect was abolished by application of glibenclamide. The above results suggest that vanadate release EDHF (Endothelium-Derived Hyperpolarizing Factor), in addition to EDRF (Endothelium-Derived Relaxing Factor) from endothelial cell. This EDHF hyperpolarize the smooth muscle cell membrane potential via opening of the ATP-sensitive K+ channel and close a voltage dependent Ca++ channel. So it is suggested that the vanadate-induced relaxation of rabbit thoracic aortic rings may be due to the combined effects of EDRF and EDHF.

Animals↗
PubMed1992

Effects of Na+, K(+)-pump inhibitors on acetylcholine-induced relaxation in the rabbit aorta.

The purpose of this study was to investigate the effects of inhibitors of the Na+, K(+)-pump and membrane depolarizing agents on endothelium-dependent acetylcholine-induced relaxation in the rabbit thoracic aorta. Aortic rings were prepared from the rabbit descending thoracic aorta and the contractility of the ring was measured in various conditions such as application of ouabain, exposure to K(+)-free Krebs-Henseleit solution and high K+. Ouabain or exposure to K(+)-free Krebs-Henseleit solution inhibited acetylcholine or sodium nitroprusside-induced relaxation. KCl also inhibited the acetylcholine or sodium nitroprusside-induced relaxation. These results suggest that the Na+, K(+)-pump may play a role in endothelium-dependent acetylcholine-induced relaxation.

Acetylcholine↗
PubMed1990

Effects of ketamine on contractile responses in vascular smooth muscle.

This study was designed to determine the effects of ketamine on contractions induced by norepinephrine (NE), K+ or histamine (Hist) and on agonist-induced calcium mobilization, in rabbit thoracic aorta with or without endothelium. Contractile responses to NE, K+ or Hist were markedly attenuated by prior exposure to ketamine. Subsequent addition of ketamine to the rabbit aorta undergoing an isometric contraction induced by NE, K+ or Hist also decreased the contractile responses in a calcium ion concentration-dependent manner. Preincubation with ketamine produced a concentration-dependent inhibition of contractile responses elicited by the addition of calcium ion (1.6 mM) to a Ca(++)-free depolarizing solution. However, the phasic contraction produced by NE with 2mM lanthanum pretreatment, which is release of intracellular calcium, was also inhibited by ketamine. Moreover, the tonic contraction produced by NE after depletion of the agonist-releasable pool of intracellular calcium, which is thought to be due to calcium influx, was depressed by ketamine. These data suggest that ketamine relaxes NE-contracted rings of rabbit thoracic aorta by decreasing calcium entry and by producing an extracellular calcium-independent relaxant effect.

Animals↗
PubMed1981

Method for separation of cells and suspending medium at high pressure.

We describe a pressure chamber designed for measuring fluxes and equilibrium distributions of substances between cells in suspension and the extracellular medium at pressures up to 400 ATA. The pressure chamber contains a filtration apparatus capable of taking four separate samples of cell-free medium from a cell suspension at timed intervals, without necessity of decompression. In addition, a high pressure injection system makes possible the addition to a cell suspension of precise quantities of agents such as ionophores or metabolic inhibitors, for observations of their effects on cell functions at pressure. The chamber of filtration apparatus functioned successfully in preliminary experiments designed to measure the equilibrium distribution of 36Cl- in human erythrocytes at high pressure.

Atmospheric Pressure↗