Does the relationship between natriuretic hormones and diastolic function differ by race?

INTRODUCTION: Heart failure develops earlier and is more prevalent in blacks than whites because of their higher incidence of hypertension and diabetes and likely subsequent diastolic dysfunction. Natriuretic peptides (NP) prevent cardiac malfunction through pressure, natriuresis action. However, whether race affects the relationships of NP action with cardiac function is unknown.
METHODS: To assess this, 55 (21 whites and 27 males) normotensive adults underwent a 2-hour protocol of 40 minutes rest, video game stressor and recovery. Mitral inflow and myocardial velocities (tissue Doppler) were recorded every 20 minutes. Blood pressure and heart rate were obtained at 10-minute intervals. Blood samples for pro-atrial NP and pro-brain NP (pro-BNP) were collected every 40 minutes.
RESULTS: There were differences in the association between (1) the changes from rest to stress for E/A ratio and double product (whites, r = -0.42; blacks, r = 0. 10; P = 0.034 for difference between correlations); (2) stress E(m) and pro-atrial NP (whites, r = 0.59; blacks, r = -0.25; P = 0.025); (3) rest E(m) and BNP (whites, r = 0.83; blacks r = -0.17; P = 000); (4) rest E(m)/A(m) and pro-BNP (whites, r = 0.70; blacks, r = -0.42; P = 0.003); (5) rest E/E(m) and pro-BNP (whites, r = -0.61; blacks, r = 0.31; P = 0.015) and (6) stress E and pro-BNP (whites, r = 0.56; blacks, r = -0.18; P = 0.043).
CONCLUSION: The higher correlations between levels of NP and diastolic function indices both at rest and stress suggest that NP protective action is more pronounced in whites than in blacks.