Strial prostaglandins and leukotrienes. Biochemical characteristics and interrelationship with furosemide.
Synthesis of prostaglandins (PGs) was characterized in the lateral wall (LW) of guinea-pig cochlea. Basal synthesis at 37 degrees C was about 480 pg/LW (12.8 ng X mg-1 protein) for PGI2 and 85 pg/LW (2.3 ng X mg-1 protein) for PGE2, levelling out after 10 min of incubation. Incubation with arachidonic acid (10(-5) M) increased PGI2 and PGE2 synthesis by 44% and 1020%, respectively, showing that arachidonic acid availability is a synthesis-limiting factor. The stimulating effect of the Ca++ ionophore A23187 (5 X 10(-6) M) on PG synthesis was weak (about +50%) but was enhanced (about +140%) by preincubation with arachidonic acid. Angiotensin II (10(-6) M), vasopressin (5 X 10(-7) M), and furosemide (10(-8) to 10(-3) M) did not alter PG secretion. Neither aspirin nor indomethacin prevented the development of furosemide ototoxicity (endocochlear potential) in the rat. Perfusion with PGI2 influenced the furosemide effect in some instances.
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D003051:Cochlea / Q000187:drug effects / Q000378:metabolism*; D015232:Dinoprostone; D011464:Epoprostenol / Q000096:biosynthesis*; D005665:Furosemide / Q000494:pharmacology*; D006168:Guinea Pigs; D008297:Male; D011458:Prostaglandins E / Q000096:biosynthesis*; D013189:SRS-A / Q000096:biosynthesis*; D013316:Stria Vascularis / Q000378:metabolism; D014667:Vasopressins / Q000494:pharmacology
D001095:Arachidonic Acids; D011458:Prostaglandins E; D013189:SRS-A; D014667:Vasopressins; D000804:Angiotensin II; D016718:Arachidonic Acid; D000001:Calcimycin; D005665:Furosemide; D011464:Epoprostenol; D015232:Dinoprostone