The effects of bFGF on the calicum influx in OHCs / 中国药理学通报

ABSTRACT

AIM To examined the effect of bFGF on the calcium influx in outer hair cells (OHCs) and its antagonistical effects with streptomycin. The aim of the study is to explore the mechanism of acute ototoxicity of streptomycin and antagonism of bFGF. METHODSE The OHCs of guinea pig were isolated using an enzyme machine methods and loaded with 10 ?mol?L -1 Fluo 3/AM for 30 min at 37℃,then cultured 60 min at room temperature. Individual Fluo 3 loaded OHCs were examined with a confocal microscope (ACAS Ultima, USA) using a 20? objective lens and linear scan mean. The fluorescent images, collected every 5 sec for 300 s, were stored in a computer. The fluorescent intensity of the images were analyzed by the software cooperated with the confocal microscope, and a function curve showing the change trend of fluorescent intensity with time was obtained. RESULTS The OHCs [Ca 2+ ] i hold steady within the process of normal extracellular liquid perfusion. OHCs [Ca 2+ ] i increased when perfused 100 mmol?L -1 high potassium media(10/11) and normal media containing 1 nmol?L -1 bFGF(9/9), but the OHCs [Ca 2+ ] i don't changes in high potassium free calcium media(7/7) and free calcium media containing 1 nmol?L -1 bFGF(8/8). After treated by 1 mmol?L -1 streptomycin, the OHCs [Ca 2+ ] i increased 0/12, 4/8 respectively when perfused high potassium media and bFGF media. And after treated by 1 nmol?L -1 bFGF, high potassium media make OHCs [Ca 2+ ] i increased more obviously and keeping longer time. After treated by 1 mmol?L -1 streptomycin, respectively, 0 1,1 and 10 nmol?L -1 bFGF make 4/11,6/9 and 12/12 OHCs [Ca 2+ ] i increasing when perfused high potassium media. CONCLUSION High potassium media and bFGF perfusion can result in increasing of OHCs [Ca 2+ ] i ,and OHCs [Ca 2+ ] i increase rooted in the calicum influx, there is synergic effects between high potassium and bFGF. The streptomycin can block the process of calcium influx induced by high potassium media and the block effects can be antagonized by bFGF, and the antagonistical effects have bFGF concentration dependence.