Urinary kallikrein excretion after renal transplantation: relationship to hypertension, graft source, and renal function.

The role of the renal kallikrein-kinin system in the pathogenesis of hypertension and various forms of renal dysfunction after human renal transplantation has been assessed by measurement of urinary kallikrein activity in 41 renal transplant recipients. The urinary tosyl arginine methyl esterase assay was used. The urinary kallikrein in these patients appeared to originate from the transplanted kidney and not their own diseased kidneys. Twenty-three recipients had hypertension (mean blood pressure 156 +/- 3/98 +/- 2 mm Hg) and excreted less kallikrein (4.0 +/- 1.2 versus 12.5 +/- 4.0 esterase units [EU] per 24 hours, p less than 0.05) than their 18 normotensive counterparts (mean blood pressure 132 +/- 2/77 +/- 1 mm Hg, both p less than 0.01). Subjects with renal complications of transplantation (acute tubular necrosis [ATN], nine patients, or acute rejection [AR], eight patients) also excreted less kallikrein than the 28 subjects without such complications (3.4 +/- 0.9 versus 10.3 +/- 2.7 EU/24 hours, p less than 0.02). Among those with acute renal complications, subjects with ATN excreted less kallikrein than those with AR (1.3 +/- 0.3 versus 5.7 +/- 1.7 EU/24 hours, p less than 0.02). Cadaver graft recipients excreted less kallikrein than living related donor graft recipients (2.1 +/- 0.4 versus 13.0 +/- 3.5 EU/24 hours, p less than 0.01), perhaps reflecting their higher blood pressures (mean systolic pressure 151 +/- 3 versus 140 +/- 3 mm Hg, p less than 0.04), relatively impaired renal function (creatinine clearance values 42 +/- 8 versus 62 +/- 5 ml/min, p less than 0.04), and higher incidence of ATN (nine cases versus none). The kallikrein-kinin system may be involved in the pathogenesis of hypertension and some forms of renal dysfunction after renal transplantation.

Nadolol: evidence for sympathetic nerve inhibition by a beta blocker in essential hypertension.

Although beta blockers' antihypertensive mechanisms have not been clearly delineated, their long-term effects may involve chronic reduction in systemic vascular resistance, which may be the result of sympathetic outflow inhibition. Although a central site of action has been advocated, we sought to identify a peripheral non-cardiac sympatholytic mechanism by studying autonomic function in a small group of nine hypertensive males during treatment with placebo and chronic oral nadolol, a noncardioselective hydrophilic beta blocker with little predicted brain penetration. Nadolol reduced blood pressure and heart rate (both P less than 0.005) while suppressing the blood pressure response to cold stimulus only after parasympathetic inhibition (P less than 0.05); the blunted response to cold stimulus did not correlate with the drug's overall blood pressure lowering effect. Baroreceptor sensitivities to phenylephrine and amyl nitrate stimuli were not enhanced. Several biochemical measures of sympathetic nervous system activity were not influenced by nadolol. Thus, nadolol, while not enhancing baroreflex sensitivity, does seem to have a peripheral non-cardiac sympatholytic effect, but this effect does not account entirely for the long term reduction in blood pressure observed in patients on the drug.

Preserved renal perfusion during treatment of essential hypertension with the beta blocker nadolol.

Several beta-adrenergic antagonists impair renal perfusion during treatment of hypertension in man. The acute and chronic effects of a new noncardioselective beta blocker, nadolol, on renal hemodynamics, intravascular volume, and renal electrolyte excretion were studied in 10 men with essential hypertension. Oral nadolol normalized systemic blood pressure without impairment of glomerular filtration rate or renal blood flow, indicating preserved renal blood flow and glomerular filtration rate autoregulation. Intravascular volume and renal excretion of electrolytes were similarly unaltered. Once-daily nadolol lowers blood pressure without renal hemodynamic of functional embarrassment.

Renal perfusion is preserved during cardioselective beta-blockade with metoprolol in hypertension.

Treatment of hypertension with beta-adrenergic blockers may impair renal perfusion, perhaps because of beta 2-blockade in the renal vascular bed. We evaluated the effects of the cardioselective (beta 1 selective) beta-blocker metoprolol upon renal hemodynamics, intravascular volume, and renal electrolyte handling in nine essential hypertensive men. Metoprolol normalized systemic BP without significant acute or chronic changes in glomerular filtration rate, renal plasma flow, or renal blood flow. Overall renal sodium excretion and fractional sodium excretion increased on chronic metoprolol, without changes in intravascular volume or renal excretion of other electrolytes. Thus, cardioselective beta-blockade with metoprolol normalizes BP without renal hemodynamic impairment.