Role of thromboxane A2 in a microcirculation disorder of the rat inner ear.
Since thromboxane (TX) A2 causes vasoconstriction and platelet aggregation, we evaluation the effect of a TXA2 receptor antagonist (vapiprost) and a TXA2 synthetase inhibitor (Y-20811) on a microcirculation disorder in the rat inner ear that was induced by a photochemical reaction between an intravenous injection of rose bengal (RB) and green light. A gradual decrease of the cochlear action potential (CAP) to an 8 kHz sound stimulus was measured with an electrocochleogram and occurred after the RB injection. The CAP then disappeared 5 min after the injection of RB. Both vapiprost and Y-20811 significantly prolonged the time required to complete suppression of the CAP as compared with saline as control. These findings indicate that TXA2 may play an important role in microcirculation disorders in the rat inner ear.
Umemura
K
K
Department of Pharmacology, Hamamatsu University School of Medicine, Japan.
Asai
Y
Y
Uematsu
T
T
Nakashima
M
M
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001300:Audiometry, Evoked Response; D001713:Biphenyl Compounds / Q000494:pharmacology; D003051:Cochlea / Q000502:physiology; D007758:Ear, Inner / Q000098:blood supply*; D011464:Epoprostenol / Q000096:biosynthesis; D006311:Hearing Disorders / Q000503:physiopathology; D006538:Heptanoic Acids / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D008833:Microcirculation / Q000187:drug effects / Q000502:physiology; D010974:Platelet Aggregation / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors; D013928:Thromboxane A2 / Q000502:physiology*; D013930:Thromboxane-A Synthase / Q000037:antagonists & inhibitors; D014661:Vasoconstriction / Q000187:drug effects
D001713:Biphenyl Compounds; D006538:Heptanoic Acids; D007093:Imidazoles; D017482:Receptors, Thromboxane; C049966:Y 20811; D013928:Thromboxane A2; D011464:Epoprostenol; D013930:Thromboxane-A Synthase; C060013:vapiprost