Percutaneous dilational tracheostomy.
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Biomedical subjects
Publications and source records attributed to F T McAuley.
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Adult Sprague-Dawley rats treated daily for 14 days with 50 mg/kg cyclosporin A (CsA) exhibited nephrotoxicity, characterized by reduced glomerular filtration rate, decreased urinary sodium and potassium flow, tubular enzymuria and proximal tubular structural damage. Elevations in plasma renin activity (PRA) were observed on day 4, but returned to normal within 7 days. Co-treatment of animals for the 14 day period with enalapril (8 mg/kg/day), a potent inhibitor of angiotensin converting enzyme (ACE), or spironolactone (25 mg/kg/day), the distal tubular antagonist of aldosterone, reduced the nephrotoxicity, although PRA remained elevated. Neither enalapril nor spironolactone affected circulating CsA levels. These data suggest that the action of aldosterone on the distal tubule may be important in the pathogenesis of CsA nephrotoxicity.
Cyclosporin A (CsA; 50, 100 or 150 mg/kg) was administered by gavage, daily for 4 days, to groups of normotensive rats. An additional group of animals received the drug vehicle. CsA-induced nephrotoxicity, characterized by reduced glomerular filtration rate (GFR) and urinary sodium flow, enzymuria and proximal tubular cell damage was accompanied by elevated plasma renin activity (PRA). These changes were dose-related at 50 and 100 mg/kg CsA, but were not increased by administration of 150 mg/kg. Circulating trough drug levels were related to dosage. Four days after CsA withdrawal in animals given 50 mg/kg, there was reduced nephrotoxicity and PRA had returned to normal, even though circulating CsA levels had not diminished. Rats given 100 and 150 mg/kg, however, showed no reduction in nephrotoxicity or in PRA. Hyperglycaemia was evident at 4 days in animals given 100 and 150 mg/kg CsA and persisted 4 days after drug withdrawal. There were no accompanying abnormalities in islet cell structure. Continuous administration of CsA (50 mg/kg) to rats for 14 days caused elevated PRA on day 4 but a return to normal levels by day 7. In contrast, significant GFR impairment was evident by day 7 whilst enzymuria was significantly increased from day 4 onwards. CsA nephrotoxicity in the rat is clearly associated with activation of the renin-angiotensin-aldosterone system. Possible mechanisms leading to increased renin release are discussed.
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The acute nephrotoxic properties of cyclosporin A (CsA) were investigated in normotensive, adult male Sprague-Dawley rats. Animals received either 50 or 100 mg CsA/kg by gastric intubation for 7 days. Within 24 h, significant increases in urinary N-acetyl-beta-D-glucosaminidase (NAG) and gamma-glutamyl transpeptidase (gamma GT) activity were observed at both doses of CsA. Renal function abnormalities, however, were not apparent until 2 days (100 mg/kg) or 7 days (50 mg/kg). Progressive increases in enzymuria were evident in both groups between 1 and 4 days, at which later time proximal straight tubular cell damage was first observed. The data obtained using this model clearly demonstrate that enzymuria provides a sensitive index of acute CsA-induced renal cell damage and that enzymuria precedes detectable renal functional and structural abnormalities.