Na/H and Li/Na exchange in red blood cells of normotensive and hypertensive patients with insulin dependent diabetes mellitus (IDDM).
It has been shown that red blood cell Li/Na exchange, also called countertransport (Li/Na CTT) is increased in patients with insulin dependent diabetes mellitus (IDDM) with clinical or subclinical nephropathy and elevated blood pressure. Because recent experimental evidence confirms that red cell Li/Na CTT is a mode of functioning of the Na/H exchange (Na/H CTT), we have measured both transport modes in 23 IDDM (16 hypertensive and seven normotensive) and in eight normotensive controls with normal glucose tolerance. Na/H and Li/Na CTT were significantly increased in hypertensive compared to normotensive diabetics and controls. Na/H CTT was 78 +/- 28 mmol/L cell/h in hypertensive IDDM, 50 +/- 21 in normotensive IDDM, and 55 +/- 24 in the controls. Li/Na CTT was 0.37 +/- 0.13 mmol/L cell/h, 0.27 +/- 0.10, and 0.25 +/- 0.11, respectively. Na/H and Li/Na CTT were significantly correlated (r = .38, P less than .05). The proximal tubule sodium reabsorption, measured as the fractional Li+ reabsorption, was significantly correlated to red cell Na/H CTT (r = .38, n = 29, P less than .05), but not to the Li/Na CTT (r = .21, n = 29). In conclusion this work confirms that Na/H and Li/Na CTT are function modes of the same transporter and that an increased activity of Na/H CTT might play a role in the blood pressure increase in IDDM.
Semplicini
A
A
Institutes of Medicina Clinica and Medicina Interna, University of Padova, Italy.
Mozzato
M G
MG
Sama'
B
B
Nosadini
R
R
Fioretto
P
P
Trevisan
R
R
Pessina
A C
AC
Crepaldi
G
G
Dal Palu'
C
C
D000328:Adult; D017920:Antiporters; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism*; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000378:metabolism*; D003928:Diabetic Nephropathies / Q000209:etiology; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D015222:Sodium Channels / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers; D014882:Water-Electrolyte Balance
D017920:Antiporters; D002352:Carrier Proteins; D015222:Sodium Channels; D017923:Sodium-Hydrogen Exchangers; C045885:sodium-lithium countertransporter