Effect of cromakalim on micturition function in rats.
Although many studies investigating the effect of cromakalim on bladder contractility exist, thus far, there are no published studies investigating its effect on micturition function in conscious rats. We measured the effect of cromakalim i.v. on urine output, frequency, volume of each micturition, and blood pressure in saline-diuresed and non-diuresed rats. In saline-diuresed rats cromakalim produced significant decreases in urine output (0.1 mg/kg, 32%; 0.3 mg/kg, 46%; 1.0 mg/kg, 68%) and average frequency (0.1 mg/kg, 36%; 0.3 mg/kg, 51%; 1.0 mg/kg, 70%) in the first 3 hours. At 3-6 hours after administration of cromakalim there were rebound increases in both urine output (0.1 mg/kg, 290%; 0.3 mg/kg, 373%; 1.0 mg/kg, 538%), and frequency (0.1 mg/kg, 147%; 0.3 mg/kg, 181%; 1.0 mg/kg, 314%) and by 6-12 hours the effects of cromakalim on micturition function were gone. Mean arterial pressure dropped to 50% of control immediately after cromakalim administration in saline-diuresed rats and began to return to control levels after 3 hours. Cromakalim produced similar results in non-diuresed rats. The decrease in urine output 0-3 hours after cromakalim administration may have been a consequence of cromakalim's profound decrease in blood pressure that occurred during that time.
Smith
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Department of Pharmacology, ICI Americas, Wilmington, Delaware 19897-2500.
Bertelsen
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DL
Kau
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Chun
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D000284:Administration, Oral; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002940:Circadian Rhythm; D019806:Cromakalim; D004231:Diuresis; D004305:Dose-Response Relationship, Drug; D007275:Injections, Intravenous; D008297:Male; D011758:Pyrroles / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012965:Sodium Chloride / Q000494:pharmacology; D013997:Time Factors; D014554:Urination / Q000187:drug effects*
D001578:Benzopyrans; D011758:Pyrroles; D019806:Cromakalim; D012965:Sodium Chloride