Failure of forskolin to elevate the endocochlear potential in kanamycin-poisoned animals.
The effect of forskolin (FSK) on the endocochlear potential (EP), K+ activity (AK), Na+ activity (ANa) and Cl- activity (ACl) in scala media (SM) was compared between normal and kanamycin (KM)-poisoned guinea pigs by means of double-barrelled ion-selective microelectrodes. The perfusion of the scala vestibuli (SV) with FSK (200 microM) produced EP elevation in normal animals whereas FSK failed to do it in KM-poisoned animals. FSK increased ACl of SM with no significant change in AK and ANa of SM in both groups of animals. Histological examination of KM-poisoned animals showed damaged outer and inner hair cells with an intact appearance of the stria vascularis. The mechanism underlying the failure of FSK to elevate the EP in KM-poisoned animals is discussed.
Department of Otolaryngology, Nara Medical University, Japan.
I
I
Kitano
K
K
Doi
N
N
Mori
M
M
Umemoto
M
M
Sakagami
K
K
Fukazawa
T
T
Matsunaga
D000818:Animals; D001693:Biological Transport, Active; D002712:Chlorides / Q000378:metabolism; D003051:Cochlea / Q000187:drug effects* / Q000473:pathology; D005576:Colforsin / Q000494:pharmacology*; D005072:Evoked Potentials, Auditory / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006168:Guinea Pigs; D007612:Kanamycin / Q000633:toxicity*; D008297:Male; D008839:Microelectrodes; D008854:Microscopy, Electron; D009925:Organ of Corti / Q000187:drug effects / Q000473:pathology*; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D002712:Chlorides; D005576:Colforsin; D007612:Kanamycin; D012964:Sodium; D011188:Potassium