[Early effects of explosion on hearing threshold and activities of Na+-K+-ATPase and succinic dehydrogenase in the stria vascularis of guinea pigs].

Slow cortex responses to several frequencies were recorded in guinea pigs before and after intense impulse noise exposure. Guinea pigs were decapitated 90 minutes after the exposure. Besides scanning electron microscopic analysis of cochleas, activities of Na(+)-K(+)-ATPase and SDH in the stria vascularis (SV) corresponding to 4 kHz were studied with histochemical methods under light microscope. Densities of histochemical reaction products and cross sections of the SV were measured with image analysis system. Activities of Na(+)-K(+)-ATPase and SDH in the SV decreased significantly in PTS group (P less than 0.01, P less than 0.05). There was no significant change in TTS group. It revealed that decrease of Na(+)-K(+)-ATPase and SDH in the SV may contribute to remarkable hearing threshold shift besides mechanical destruction by noise. Metabolic disturbance may aggravate hair cell damage. Direct damage of the SV caused by intense impulse noise may be one of the causes of PTS.