Objective: This study was undertaken to investigate the effects of Ginaton, a kind of extract of gingko biloba with vasoactive, on cochlear blood flow, and to provide the experimental basis for the clinical drug usage.
Method: Ninety-six guinea pigs were divided into two groups at random, 56 for intravenous infusion (i.v.) group, and 40 for round window membrane (RWM) application group. According to the preliminary results, i.v. group had five subgroups: control, 2.8 mg/kg, 3.5 mg/kg, 3.85 mg/kg, 4.2 mg/kg. RWM group had four sub-groups: control, 3.5 g/L, 0.35 g/L, 0.035 g/L. Ginaton and vehicle were infused through the cervical vein by micropump in 5 minutes. In RWM group, 2 microliters vehicle were dropped into RWM. Cochlear microcirculation was monitored by laser doppler flowmeter (LDF), and mean arterial blood pressure (MABP), which transferred by force transducers and preamplifier, were simultaneously recorded at the computer.
Result: Cochlear blood flow (CBF) decreased 4.95% and CMBC decreased 6.32% in 3.5 g/L RWM group, and in 0.35 g/L RWM group, these two figures decreased individually 4.75%, 7.61%. In control and 2.8 mg/kg group cochlear microcirculation and MABP had no significant changes. In other i.v. groups, CBF increased 4.53%, 5.21%, 6.65% after 3.5 mg/kg, 3.85 mg/kg, 4.2 mg/kg drugs had been infused, and dosage-effect relation existed. Only in 3.85 mg/kg group, MABP decreased 8.69%.
Conclusion: Ginaton could improve CBF in a limited dosage range, and this increase showed dose-dependent relation. The mechanism that Ginaton affected the cochlear microcirculation was different because of the way of drug usage.