OBJECTIVETo investigate the approach of basic fibroblast growth factor(bFGF) entering inner ear, as well as its the protective mechanism to inner ear and nerve tissue in pathological situation.

METHODS125I-bFGF was injected into guinea pigs body via the lateral ventricle and muscle under physical situation as well as pathological situation. Then the per minute gamma-radioactive in blood, liver, thyroid gland, brain, cochlear and perilymph fluid was counted, and the distribution and metabolism of bFGF in the inner ear and autoradiography of the cochlea were also observed.

RESULTSGamma-radioactive cpm of blood and liver increased significantly, while it did not change in brain, cochlea and perilymph after 125I-bFGF intramuscular injections. Gamma-radioactive cpm in blood, liver, brain, perilymph and cochlea had increased and autoradiography granules was found in the cochlea in 30 min after 125I-bFGF injected into CSF. In brain, perilymph and cochlea, a maximal value of gamma-radioactive cpm was obtained between 2 h and 4 h, while that in 8 h decreased significantly. Autoradiography granules still were seen in 8 h. gamma-radioactive cpm in 12 h was still higher than that in control group, but autoradiography granules can't be seen. The result in 24 h was similar to that in control group. The time course of cpm in the blood, cochlea and perilymph always parallel changed.

CONCLUSIONSbFGF has some difficulties in getting across blood-labyrinth barrier (BLB) and blood-brain barrier (BBB) under physical and pathological situation, such as acute anoxia, aminoglycoside-induced deafness. bFGF can reach inner ear, perilymph fluid, brain tissue and blood rapidly when it is injected into CSF and excreted slowly in those tissues. Permeability of BBB and BLB to bFGF is similar and has orientation.