The distribution and location of atrial natriuretic peptides(ANP) in the cochlear stria vaseularis of normal guinea pigswere studied to find out regional regulating factors of cochlearblood flow (CBF) and productive f...The distribution and location of atrial natriuretic peptides(ANP) in the cochlear stria vaseularis of normal guinea pigswere studied to find out regional regulating factors of cochlearblood flow (CBF) and productive foundation of cochlearendolymph by ABC immunocytochemistry and immunoele-ctronmicroscopy. The ANP-IR products were seen in the striavascularis of the 1-4 turns of the lateral wall of the cochlea,more markedly along its margin; and were negative in the spi-ral ligaments. Immunoelectronmicroscopically, a plenty ofsphericals of 250-350nm in diameter were noted in thecytoplasm of marginal and intermediate cells, but few in thebasal cells. The results suggest that the cochlear striavascularis had the function of secreting ANP in the guinea pig.展开更多
Over the past two decades considerable progress has been made in understanding the ototoxic effects and mechanisms underlying loop diuretics. As typical representative of loop diuretics ethacrynic acid or furosemide o...Over the past two decades considerable progress has been made in understanding the ototoxic effects and mechanisms underlying loop diuretics. As typical representative of loop diuretics ethacrynic acid or furosemide only induces temporary hearing loss, but rarely permanent deafness unless applied in severe acute or chronic renal failure or with other ototoxic drugs. Loop diuretic induce unique pathological changes in the cochlea such as formation of edematous spaces in the epithelium of the stria vascularis, which leads to rapid decrease of the endolymphatic potential and eventual loss of the cochlear microphonic potential, summating potential, and compound action potential. Loop diuretics interfere with strial adenylate cyclase and Nat/Kt-ATPase and inhibit the Na-K-2Cl cotransporter in the stria vascularis, however recent reports indicate that one of the earliest effects in vivo is to abolish blood flow in the vessels supplying the lateral wall. Since ethacrynic acid does not damage the stria vascularis in vitro, the changes in Nat/Kt-ATPase and Na-K-2Cl seen in vivo may be secondary effects results from strial ischemia and anoxia. Recent observations showing that renin is present in pericytes surrounding stria arterioles suggest that diuretics may induce local vasoconstriction by renin secretion and angiotensin formation. The tight junctions in the blood-cochlea barrier prevent toxic molecules and pathogens from entering cochlea, but when diuretics induce a transient ischemia, the barrier is temporarily disrupted allowing the entry of toxic chemicals or pathogens.展开更多
Objective To record the endocochlear potential (EP) and calculate potassium concentration [K+] in Minipig cochleae. Methods We used multi-barreled electrodes to measure the EP and the potential, [K + ]. EP and potassi...Objective To record the endocochlear potential (EP) and calculate potassium concentration [K+] in Minipig cochleae. Methods We used multi-barreled electrodes to measure the EP and the potential, [K + ]. EP and potassium electrode recording were made in 9 cochleae from 5 minipigs to get normal EP values. Results The average EP value in the cochlea from the minipigs was 77.3 ± 14 mV. The average [K+] for the minipigs was 147.1 ± 13 mM. Conclusions The EP and potential, [K + ] in minipigs are lower than in the human and rodents. This may be the reason why porcine ABR thresholds are slightly higher than humans and rodents.展开更多
文摘The distribution and location of atrial natriuretic peptides(ANP) in the cochlear stria vaseularis of normal guinea pigswere studied to find out regional regulating factors of cochlearblood flow (CBF) and productive foundation of cochlearendolymph by ABC immunocytochemistry and immunoele-ctronmicroscopy. The ANP-IR products were seen in the striavascularis of the 1-4 turns of the lateral wall of the cochlea,more markedly along its margin; and were negative in the spi-ral ligaments. Immunoelectronmicroscopically, a plenty ofsphericals of 250-350nm in diameter were noted in thecytoplasm of marginal and intermediate cells, but few in thebasal cells. The results suggest that the cochlear striavascularis had the function of secreting ANP in the guinea pig.
基金supported in part by a grant from National Natural Science Foundation of China 81470706a grant from Guangdong Natural Science Foundation No 2015A030313180
文摘Over the past two decades considerable progress has been made in understanding the ototoxic effects and mechanisms underlying loop diuretics. As typical representative of loop diuretics ethacrynic acid or furosemide only induces temporary hearing loss, but rarely permanent deafness unless applied in severe acute or chronic renal failure or with other ototoxic drugs. Loop diuretic induce unique pathological changes in the cochlea such as formation of edematous spaces in the epithelium of the stria vascularis, which leads to rapid decrease of the endolymphatic potential and eventual loss of the cochlear microphonic potential, summating potential, and compound action potential. Loop diuretics interfere with strial adenylate cyclase and Nat/Kt-ATPase and inhibit the Na-K-2Cl cotransporter in the stria vascularis, however recent reports indicate that one of the earliest effects in vivo is to abolish blood flow in the vessels supplying the lateral wall. Since ethacrynic acid does not damage the stria vascularis in vitro, the changes in Nat/Kt-ATPase and Na-K-2Cl seen in vivo may be secondary effects results from strial ischemia and anoxia. Recent observations showing that renin is present in pericytes surrounding stria arterioles suggest that diuretics may induce local vasoconstriction by renin secretion and angiotensin formation. The tight junctions in the blood-cochlea barrier prevent toxic molecules and pathogens from entering cochlea, but when diuretics induce a transient ischemia, the barrier is temporarily disrupted allowing the entry of toxic chemicals or pathogens.
文摘Objective To record the endocochlear potential (EP) and calculate potassium concentration [K+] in Minipig cochleae. Methods We used multi-barreled electrodes to measure the EP and the potential, [K + ]. EP and potassium electrode recording were made in 9 cochleae from 5 minipigs to get normal EP values. Results The average EP value in the cochlea from the minipigs was 77.3 ± 14 mV. The average [K+] for the minipigs was 147.1 ± 13 mM. Conclusions The EP and potential, [K + ] in minipigs are lower than in the human and rodents. This may be the reason why porcine ABR thresholds are slightly higher than humans and rodents.
