Does endogenous or exogenous adenosine facilitate the functional recovery of the cochlea after ischemia?
The present study was undertaken to determine whether adenosine attenuates cochlear dysfunction induced by transient ischemia. Adenosine or erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), an adenosine deaminase inhibitor, was administered by perilymphatic perfusion to albino guinea pigs that were subjected to cochlear ischemic episodes of 30-minute duration. The threshold shift of the compound action potential (CAP) from the preischemic value was significantly reduced in the animals perfused with EHNA 1 hour after the onset of reperfusion. However, perfusion of adenosine at concentrations of 100 micromol/L to 10 mmol/L did not reduce the postischemic CAP threshold shift by either 1 hour or 4 hours after the onset of reperfusion. These results suggest that the elevation of the adenosine concentration did not exert a protective effect on the cochlear ischemia-reperfusion injury, and that the protective action of EHNA is unrelated to elevating the adenosine concentration.
Tabuchi
Keiji
K
Department of Otolaryngology, Institute of Clinical Medicine, University of Tsukuba, Japan.
Tsuji
Shigeki
S
Asaka
Yasutoshi
Y
Ito
Zenya
Z
Hara
Akira
A
Kusakari
Jun
J
D000200:Action Potentials; D000225:Adenine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D000241:Adenosine / Q000008:administration & dosage / Q000494:pharmacology* / Q000502:physiology*; D058892:Adenosine Deaminase Inhibitors; D000818:Animals; D003051:Cochlea / Q000098:blood supply* / Q000502:physiology* / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D006168:Guinea Pigs; D007511:Ischemia / Q000503:physiopathology*; D020127:Recovery of Function; D015427:Reperfusion Injury / Q000517:prevention & control*; D013997:Time Factors; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
D058892:Adenosine Deaminase Inhibitors; D004791:Enzyme Inhibitors; D014665:Vasodilator Agents; C010192:9-(2-hydroxy-3-nonyl)adenine; D000225:Adenine; D000241:Adenosine