[Effects of extrastimulation on morphofunctional state of cochlear stria vascularis]

An electron-microscopic study of the response of cochlear stria vascularis (CSV) cells to an electric impact of physiotherapeutic parameters was made in 26 guinea-pigs. Twelve guinea-pigs (group 1) have undergone 9 sessions of bilateral endaural electrostimulation with square bipolar impulses (4 ms, 0.1-0.4 mA, 50 Hz, 20 min). Fourteen guinea-pigs of group 2 have undergone a 12-18-day course of intramuscular ototoxic antibiotic canamycin in a dose 200-400 mg/day followed by the above electrostimulation. Nine anesthesized guinea-pigs of group 3 were inserted an electrode into the niche of the round window of the right ear. After a 10-day course of canamycin (200 mg/day) they were exposed to electrostimulation (8 sessions) with impulsed alternative current (100 Hz, 1 ms, 0.08 mA, 30 min). Five guinea-pigs served control. Morphofunctional state of CSV was assessed at electronograms by analyzing cell ultrastructure and counting the number of secretory vacuoles in the apical region of marginal cell cytoplasm. In group 1 there was intensification of biosynthetic processes in all CSV cells and a significant (p<0.01) increase of vacuole number in the marginal cells (53.9+/-3.8) vs normal value (33.9+/-1.5). In group 2 ultrastructure of all CSV cells was less affected and secretory activity was almost normal (31.4+/-2.9). CSV cell condition was similar to ultrastructure of the cells in group 2. The number of vacuoles in CSV marginal cells of the right (28.9+/-1.98) and left (29.1+/-5.4) cochleas was similar. Thus, electrostimulation activates biosynthetic processes in CSV structures and enhances secretory activity of marginal cells.