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Increased sodium-lithium countertransport activity in red cells of IgA nephropathy patients
R Boero1, E Degli Esposti, A Fabbri
1Istituto di Nefro-Urologia dell'Università, Divisione di Nefrologia e Dialisi, Ospedale G. Bosco, Torino, Italy.
Insights
Sodium-lithium (Na,Li) countertransport activity is elevated in hypertensive IgA nephropathy patients, correlating with blood pressure and hyperlipidemia. This erythrocyte transport mechanism is a significant independent predictor of hypertension in this patient group.
Area of Science:
- Nephrology
- Cardiovascular Physiology
- Biochemistry
Background:
- Immunoglobulin A (IgA) nephropathy is a common glomerular disease.
- Hypertension and dyslipidemia are frequent comorbidities in IgA nephropathy.
- Erythrocyte Na,Li countertransport is a marker of sodium handling and blood pressure regulation.
Purpose of the Study:
- To investigate Na,Li countertransport activity in patients with IgA nephropathy.
- To determine the relationship between Na,Li countertransport and blood pressure status.
- To assess the association with lipid profiles in IgA nephropathy patients.
Main Methods:
- Evaluated 49 IgA nephropathy patients and 36 healthy controls.
- Measured erythrocyte Na,Li countertransport activity.
- Utilized logistic regression analysis to identify independent predictors of blood pressure.
Main Results:
- Na,Li countertransport was significantly higher in hypertensive IgA nephropathy patients compared to normotensive patients and controls.
- Normotensive IgA nephropathy patients showed no difference in Na,Li countertransport compared to controls.
- Elevated Na,Li countertransport was also observed in hyperlipidemic patients.
- Na,Li countertransport, proteinuria, plasma potassium, and age were independent predictors of blood pressure status.
Conclusions:
- Increased erythrocyte Na,Li countertransport activity is associated with hypertension in IgA nephropathy.
- This ion transport abnormality may play a role in the pathogenesis of hypertension in IgA nephropathy.
- Na,Li countertransport could serve as a potential biomarker for cardiovascular risk in IgA nephropathy.
Abstract:
The aim of this work was to analyze Na,Li countertransport activity in the erythrocytes from patients with IgA nephropathy, in relationship with their blood pressure status and lipid profile. Forty-nine patients (32 males, 17 females) with biopsy-proven IgA nephropathy and without significant impairment of renal function (serum creatinine less than or equal to 1.4 mg/dl) and 36 normal subjects (21 males, 15 females) were evaluated. Twenty-nine patients with IgA nephropathy were normotensive and 20 hypertensive (diastolic pressure greater than or equal to 95 mm Hg or treated by antihypertensive drugs). Na,Li countertransport was significantly higher in red cells from hypertensive than from normotensive patients (P = 0.002) and normal subjects (P = 0.0001), (values respectively 309 +/- 17; 241 +/- 12 and 211 +/- 11 mumol/liter RBC/hr); normotensive patients with IgA nephropathy did not differ from controls regarding the Na,Li countertransport rate. A multiple stepwise logistic regression analysis with blood pressure status as the dependent variable and Na,Li countertransport activity, age, serum creatinine, proteinuria, cholesterol, triglycerides, plasma potassium and time from onset as independent variables, indicated an independent significant association for Na,Li countertransport (P = 0.002) proteinuria (P = 0.006), plasma potassium (P = 0.006) and age (P = 0.029). Other tested variables were not independently related to blood pressure status. Hyperlipidemic patients (plasma total cholesterol concentration greater than 200 mg/dl and/or plasma triglycerides greater than 172 mg/dl) had an erythrocyte Na,Li countertransport activity significantly higher than normolipidemic (P = 0.005) and controls (P = 0.001) (values respectively 295 +/- 14; 226 +/- 12 and 211 +/- 11 mumol/liter RBC/hr).(ABSTRACT TRUNCATED AT 250 WORDS)