Red blood cell Na+/H+ and Li+/Na+ exchange in patients with essential hypertension.
The increased red blood cell Li+/Na+ exchange found in a subgroup of patients with essential hypertension (EH) may reflect an increased activity of the Na+/H+ exchange. The maximal velocity of the red cells' Na+/H+ (Na+ influx promoted by an outward H+ gradient) and Li+/Na+ (Li+ efflux promoted by external Na+) exchange were therefore measured in 41 EH and in 21 normotensive controls (NT). Both transporters were significantly higher in EH than in NT (74 +/- 39 mmol/L cell x h v 43 +/- 27 for the former, P less than .03, and 0.35 +/- 0.16 v 0.26 +/- 0.10 for the latter, P less than .05). Even though more than 100 times faster, Na+/H+ exchange was weakly but significantly correlated to Li+/Na+ exchange (r = 0.29, P less than .05). Proximal tubule Na+ reabsorption (fractional renal Li+ reabsorption) was significantly greater in EH than in NT (0.78 +/- 0.07, n = 32, v 0.73 +/- 0.06, n = 10, P less than .05) but it was not correlated to either the red cells' Na+/H+ or Li+/Na+ exchanges. Therefore, hyperactivity of Na+/H+ exchange in EH may play a role in blood pressure elevation through mechanisms other than stimulation of renal Na+ reabsorption.
Semplicini
A
A
Clinical Medica I, Universitá di Padova, Italy.
Canessa
M
M
Mozzato
M G
MG
Ceolotto
G
G
Marzola
M
M
Buzzaccarini
F
F
Casolino
P
P
Pessina
A C
AC
D000042:Absorption; D017920:Antiporters; D002352:Carrier Proteins / Q000097:blood*; D003404:Creatinine / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000235:genetics / Q000503:physiopathology; D008094:Lithium / Q000493:pharmacokinetics; D008297:Male; D008499:Medical Records; D012737:Sex Factors; D017923:Sodium-Hydrogen Exchangers
D017920:Antiporters; D002352:Carrier Proteins; D017923:Sodium-Hydrogen Exchangers; C045885:sodium-lithium countertransporter; D008094:Lithium; D003404:Creatinine