Inhibition of salicylate on potassium channels in rat inferior colliculus neurons / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To understand what role of the transient outward potassium channels and the delayed rectifier potassium channels play in the mechanism of salicylate-induced tinnitus.</p><p><b>METHODS</b>The effects of salicylate on the transient outward potassium channels and the delayed rectifier potassium channels in freshly dissociated inferior colliculus neurons of rats were studied, using the whole-cell voltage clamp method.</p><p><b>RESULTS</b>Salicylate blocked the transient outward potassium current (I(K(A and the delayed rectifier potassium current (I(K(DR in concentration-dependent manner (0.1-1 mmol/L). The IC50 values for the blocking action of salicylate on I(K(A)) and I(K(DR)) were 2.27 and 0.80 mmol/L, respectively. At a concentration of 1 mmol/L, salicylate did not shift the activation and inactivation curves of I(K(A)), but significantly shifted the activation and inactivation curves of I(K(DR)) negatively by approximately 11 mV and 24 mV.</p><p><b>CONCLUSIONS</b>Salicylate inhibits both I(K(A)) and I(K(DR)) in rat inferior colliculus neurons but only significantly affects the activation and inactivation kinetics of I(K(DR)). Effects of I(K(A)) and I(K(DR)), especially I(K(DR)), by salicylate may play an important role in salicylate-induced tinnitus.</p>

Effect of testosterone propionate on the distribution pattern of calcitonin gene-related peptide in different motoneuron pools / 中国医学科学院学报

<p><b>OBJECTIVE</b>To study the effect of testosterone propionate (TP) on the distribution pattern of calcitonin gene-related peptide (CGRP) in two types of motoneuron (Mn) pools in rats.</p><p><b>METHOD</b>The double labeling of cholera toxin B subunit coupled with colloidal gold (CB-Au) retrograde identification combining with immunocytochemistry was mainly used to reveal the distribution pattern of CGRP-like immunoreactivity (CGRP-LI) and its changes in the motoneuron pools labeled by CB-Au.</p><p><b>RESULT</b>TP injected intramuscularly 28 days later significantly decreased CGRP expression in Mn pool innervating extensor digitorum longus (EDL, fast-twitch), comparing with corresponding control and castration group respectively (P < 0.001), while no significant effect on Mn pools innervating soleus (SOL, slow-twitch, P > 0.05) was observed.</p><p><b>CONCLUSION</b>EDL-Mn pool is more sensitive to testosterone propionate than SOL-Mn pool in regulating CGRP expression.</p>