Protective effect of intrarenal calcium membrane blockers before and after renal ischemia

Abstract. The present study examined whether a pre- or postischemic infusion of verapamil (V) or a postischemic infusion of nifedipine (N), drugs which block calcium (Ca"+) influx across plasma membranes, provides protection against ischemic acute renal failure (ARF) in dogs. Renal hemodynamics and excretory function were examined 1 h (initiation phase) and 24 h (maintenance phase) after a 40-min intrarenal infusion of norepinephrine (NE). In each case, the uninfused contralateral kidney served as control. Four groups were studied: (a) dogs receiving NE alone; (b) dogs receiving an intrarenal infusion of V for 30 min before NE (V + NE); (c) dogs in which intrarenal V was infused for 2 h, beginning immediately after completion of NE infu-sion (NE + V); and (d) dogs in which intrarenal N was infused for 2 h, beginning immediately after completion of NE infusion (NE + N). Glomerular filtration rate (GFR) in the NE kidneys, as assessed by inulin clearance, at 1 and 24 h averaged 2.4 ± 1.1 and 5.0±2.0 ml/min, respectively, as compared with control kidney GFRs of 28.0±3.5 and 43.8±5.0 ml/min, respectively (both at least P < 0.01). In the V + NE group, GFR at 1 and 24 h averaged 15.0±5.5 and 31.0±4.5 ml/min, respec-tively, both at least P < 0.05 as compared with values from NE kidneys. GFRs in the NE + V group averaged 15.0±2.4 and 16.3±3.6 ml/min at 1 and 24 h, both at least P < 0.02 as compared with values from NE kidneys. GFR in the NE + N group averaged 18.6±6.0 ml/mi