Racial differences in renal kallikrein excretion: Effect of the ovulatory cycle.

Racial differences in renal kallikrein excretion: Effect of the ovulatory cycle. Background. Renal kallikrein excretion is diminished in essential hypertension, especially in African-Americans, and evidence exists for a major gene effect on the kallikrein phenotype. In addition, urinary kallikrein excretion differs by gender, with ovulating females having greater kallikrein excretion than males or postmenopausal females. Recent studies have shown that renal kallikrein excretion varies in females during the ovulatory cycle, with levels rising during the luteal phase and returning during the follicular phase to levels that are similar to those of males. In family studies, gender differences in urinary kallikrein excretion were present in white subjects, but not black subjects. We therefore hypothesized dysregulation of kallikrein biosynthetic responses in African-Americans. Methods . We determined urinary kallikrein activity [chromogenic substrate S2266 (D-val-leu-arg-paranitroanilide) assay; in μU/mg creatinine] in white (N = 15) and black (N = 11) ovulating females during the ovulatory cycle. Serum progesterone, estrogen, plasma renin activity as well as urinary aldosterone, and urinary electrolytes were determined to investigate changes between mid-follicular and mid-luteal phases in the two groups. Results . White and black groups were matched for age, body mass index, blood pressure, heart rate and renal function. Ovulatory cycle phases were confirmed by serum progesterone determinations, which increased significantly in whites and blacks to a comparable degree [0.84 ± 0.14 nmol/liter (mid-follicular) to 29.77 ± 4.70 nmol/liter (mid-luteal) in whites, 0.67 ± 0.08 nmol/liter (mid-follicular) to 28.62 ± 5.83 nmol/liter (mid-luteal) in blacks; P < 0.001 for cycle effect, P = NS for race effect and race X cycle interaction]. Urinary kallikrein activity increased from 623 ± 86 μU/mg creatinine (mid-follicular) to 948 ± 142... [ABSTRACT FROM AUTHOR]