We recently reported that when dietary potassium was controlled at a marginally deficient intake not uncommon in many African- Americans (blacks), 30 mmol/d, salt sensitivity occurred in the majority of normotensive blacks but in relatively few normotensive Caucasian-Americans (whites), and on average was more severe in blacks. In a subsequent study of normotensive and mildly hypertensive black men consuming a diet marginally deficient in potassium, we observed that in those who were salt- sensitive, dietary NaCl loading induced a renal vasoconstrictive dysfunction in which renal blood flow (RBF) decreased, renal vascular resistance (RVR) and filtration (FF) increased, and glomerular filtration rate trended upward. The changes in mean arterial pressure induced by dietary NaCl varied inversely with those induced in RBF and directly with those in RVR and FF. In those blacks who were not salt-sensitive, renal dysfunction was not observed with NaCl loading. Since dietary loading of sodium citrate (and other non-Cl sodium salts) fails to induce a pressor response in patients with salt-sensitive hypertension, sodium citrate might also fail to induce a renal vasoconstrictive dysfunction in normotensive salt-sensitive blacks. We anticipate this finding, and will interpret it as evidence suggesting that the pressor effect induced in blacks by NaCl loading requires the induction of a renal vasoconstrictive dysfunction, which in turn requires the Cl- component of loaded NaCl. We have recently reported that in the stroke-prone spontaneously hypertensive rat fed a normal NaCl diet, supplemental KCl induced a persisting exacerbation of hypertension, renal vasculopathy and strokes, whereas supplemental KHCO3 had opposite effects. When this rat was NaCl-loaded, supplemental KCl, but not KHCO3, further exacerbated hypertension and the renal vasculopathy, increased the frequency of strokes, and within hours induced a reduction in urinary creatinine excretion. In normotensive and mildly hypertensive blacks fed a normal NaCl diet (150mmol/d) just adequate in potassium (45 mmol/d), we will determine whether KCl and K-citrate (100 mmol/d) supplemented for 14 days have differing pressor and renal hemodynamic effects. We anticipate that both supplemented potassium salts will induce a decrease in blood pressure, but that a lower RBF and a higher RVR and FF will attend supplemental KCl. We will interpret such findings as suggesting that the Cl component of KCl can exert a renal vasoconstrictive and potentially renopathic effect despite a concomitant decrease in blood pressure.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL064230-01
Application #
6042212
Study Section
Special Emphasis Panel (ZRG1-CCVS (01))
Project Start
2000-02-15
Project End
2003-01-31
Budget Start
2000-02-15
Budget End
2001-01-31
Support Year
1
Fiscal Year
2000
Total Cost
$249,416
Indirect Cost
Name
University of California San Francisco
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
073133571
City
San Francisco
State
CA
Country
United States
Zip Code
94143
Kurtz, Theodore W; DiCarlo, Stephen E; Pravenec, Michal et al. (2018) Testing Computer Models Predicting Human Responses to a High-Salt Diet. Hypertension 72:1407-1416
Kurtz, Theodore W; DiCarlo, Stephen E; Pravenec, Michal et al. (2018) Functional foods for augmenting nitric oxide activity and reducing the risk for salt-induced hypertension and cardiovascular disease in Japan. J Cardiol 72:42-49
Kurtz, Theodore W; DiCarlo, Stephen E; Morris Jr, R Curtis (2016) Logical Issues With the Pressure Natriuresis Theory of Chronic Hypertension. Am J Hypertens 29:1325-1331
Morris Jr, R Curtis; Schmidlin, Olga; Sebastian, Anthony et al. (2016) Vasodysfunction That Involves Renal Vasodysfunction, Not Abnormally Increased Renal Retention of Sodium, Accounts for the Initiation of Salt-Induced Hypertension. Circulation 133:881-93
Kurtz, Theodore W; DiCarlo, Stephen E; Pravenec, Michal et al. (2016) An alternative hypothesis to the widely held view that renal excretion of sodium accounts for resistance to salt-induced hypertension. Kidney Int 90:965-973
Schmidlin, Olga; Tanaka, Masae; Sebastian, Anthony et al. (2010) Selective chloride loading is pressor in the stroke-prone spontaneously hypertensive rat despite hydrochlorothiazide-induced natriuresis. J Hypertens 28:87-94
Schmidlin, Olga; Forman, Alex; Sebastian, Anthony et al. (2007) Sodium-selective salt sensitivity: its occurrence in blacks. Hypertension 50:1085-92
Schmidlin, Olga; Sebastian, Alex Forman Anthony; Morris Jr, R Curtis (2007) What initiates the pressor effect of salt in salt-sensitive humans? Observations in normotensive blacks. Hypertension 49:1032-9
Morris Jr, R Curtis; Schmidlin, Olga; Frassetto, Lynda A et al. (2006) Relationship and interaction between sodium and potassium. J Am Coll Nutr 25:262S-270S
Schmidlin, Olga; Tanaka, Masae; Bollen, Andrew W et al. (2005) Chloride-dominant salt sensitivity in the stroke-prone spontaneously hypertensive rat. Hypertension 45:867-73

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