Study Of Blockade Action And Significance Of Agents On Voltage-gated Kv1.3 And Kv1.5

Part one High extracellular potassium ion concentration attenuates the blockade action of Ketanserin on Kv1.3 channels expressed in Xenopus oocytesObjective:To investigate the pharmacological effect of Ketanserin (KT) on Kv1.3 potassium channel and channels kinetics influenced by different extracellular potassium ion concentration and explore the potential immunomodulatory therapeutic implications of ketanserin through inhibiting Kv1.3 channel and potassium channels blocker application efficacy during the alteration of channel kinetics contributed to the electrolytes imbalances.Material and Methods:Kv1.3 channels were expressed in Xenopus oocytes, and currents were measured using the two-microelectrode voltage-clamp technique.Results: KT blocked Kv1.3 channel currents in concentration-, time-dependent and voltage-independent manner and accelerated the activation and inactivation of Kv1.3 channel current. Kv1.3 current amplitude was increased by high extracellular [K+] in concentration-dependent manner. KCl made left shift of activation and inactivation curve of Kv1.3 current and accelerated the activation and inactivation time constant. High extracellular [K+] attenuated the blockade action of ketanserin on Kv1.3 Channels. While in the presence of KT and KCl the activation and inactivation time constant were not influenced significantly no matter which was administered first.Conclusion: Kv1.3 channel's blockade by KT through binding to the open state of Kv1.3 channel and increasing by high extracellular [K+] might be involved in KT and potassium ion's potential immunomodulatory effect. High [K+]o could attenuates the blockade action of ketanserin on Kv1.3 channels, which indicated ion channels inhibitor could not possibly play its most effective therapeutic action in the presence of high [K+]o or other electrolyte disorder for the modulation of channels kinetics by electrolyte. Part Two Amiodarone Blockes Kv1.3 and Kv1.5 channels and modulates immunologic function of in vitro activated T lymphocyteObjective: Through investigating amiodarone's blockade action on Kv1.3 and Kv1.5 channels and modulation effect on phenotypic distribution of in vitro activated T lymphocyte, and on the production of cytokine in lipopolysaccharide-induced human peripheral blood lymphocytes, to elucidate one of mechanisms of immunomodulation of amiodarone. Through investigating the blockade action of amiodarone on voltage-gated Kv1.5 potassium channels, to discuss clinical implication of the pharmacological effect of amiodarone on Kv1.5 potassium channel.Methods: Kv1.3 and Kv1.5 potassium channel current expressed in Xenopus oocytes was recorded and observed the effect influenced by amiodarone using standard two-microelectrode voltage clamp techniques. The isolated human peripheral blood lymphocytes were stimulated by Ionomycin and PMA, co-administrated with or without Amiodarone, percentage of CD3+CD4+T and CD3+CD8+T lymphocyte were measured with flow cytometer after double-antibody label. The isolated human peripheral blood lymphocytes were stimulated by lipopolysaccharide, co-administrated with or without amiodarone, respectively. the concentrations of cytokine IL-2, TNF-α, IL-10 and TGF-β1 in collected supernatants were detected with ELISA.Results: (1) Amiodarone produced a concentration-dependent inhibition effect on Kv1.3 channels current and the IC50 is 3.43μM. The blockade was voltage-independent. (2) Amiodarone had no significant blockade effect on Kv1.5 channels. (3) The phenotypic distribution proportion of CD3+CD4+ and CD3+CD8+ T cell and CD3+CD4+/CD3+CD8+ ratio in activated control group in the peripheral blood compared with those in the normal group(P>0.05). Amiodarone increased significantly the percentage of CD3+CD8+ T cell compared with that in activated control group and then decreased significantly ratio of CD3+CD4+/CD3+CD8+ T lymphocytes(P<0.01).(4) Amiodarone could inhibit the production of pro-inflammation cytokines IL-2, TNF-αand anti-inflammation cytokine TGF-β1 in lipopolysaccharide-stimulated human peripheral blood lymphocytes and increase the production of anti-inflammation cytokine IL-10. The effective tendency of amiodarone on cytokine was coincident.Conclusion: Amiodarone block inactivated-state Kv1.3 channels, which was possibly one of mechanisms on its immunomodulatory effect. Amiodarone had no significant blockade promoted the special Kv1.5 channel inhibitor's clinical application.Part Three Blockade action of telmisartan and irbesartan on voltage-gated Kv1.3 and Kv1.5 potassium channels expressed in Xenopus oocytesObjective: To discuss clinical implication of the pharmacological effect of telmisartan and irbesartan on Kv1.3 and Kv1.5 potassium channel through investigating the blockade action of telmisartan and irbesartan on voltage-gated Kv1.3 and Kv1.5 potassium channels.Methods: Kv1.3 and Kv1.5 potassium channel current expressed in xenopus oocytes were recorded and observed the effect influenced by telmisarta and irbesartan using standard two-microelectrode voltage clamp techniques.Results: (1) Telmisartan and irbesartan produced concentration-dependent inhibition effect on Kv1.3 channels current and the IC50 were 2.05μM and 2.46μM, respectively. The blockade actions were both voltage-dependent. (2) Telmisartan and irbesartan produced concentration-dependent inhibition effects on Kv1.5 channels current and the IC50 were 2.37μM and 0.47μM. The blockades were significantly voltage-dependent.Conclusions: Telmisartan and irbesartan block open-state Kv1.3 channels, which were possibly one of mechanisms on its immunomodulatory and anti-atherosclerosis effect. Telmisartan and irbesartan block open-state Kv1.5 channels, which possibly partly accont for its effect of decreasing the incidence of atrial fibrillation.