Abstract
In clinical practice, an increasing number of patients exhibit concurrent cardiac and renal dysfunction, known as "cardiorenal syndrome," where each condition exacerbates the other, resulting in poorer patient prognosis. Fluid and sodium retention can lead to excessive fluid overload in the body; therefore, correcting fluid and sodium metabolic disorders is crucial for alleviating patient symptoms. This study was to investigate the abnormalities in water and sodium metabolism, as well as the expression levels of arginine vasopressin receptor 1a (AVPR1a) and arginine vasopressin receptor 2 (AVPR2), in a rat model of chronic renal failure-chronic heart failure (CRF-CHF). One hundred male Sprague-Dawley rats were randomly assigned into four groups: the CG group (normal feeding), the CRF group (3/4 nephrectomy using a "two-step surgical method"), the CHF group (subcutaneous injection of isoproterenol at 100 mg/kg), and the CRF-CHF group (3/4 nephrectomy followed by a subcutaneous injection of isoproterenol at 100 mg/kg 1 week later). 4 weeks post-surgery, urine and blood samples were collected to measure 24 h urinary protein, sodium, and potassium levels. Serum creatinine (SCr) and blood urea nitrogen (BUN) levels were determined using assay kits. Left ventricular end diastolic pressure (LVEDP) and left ventricular systolic pressure (LVSP) were measured via left ventricular catheterization. The heart was weighed to calculate the left ventricular weight to body weight ratio (LVW/BW). The renal cortex and medulla were isolated to assess the relative mRNA and protein expression levels of AVPR1a and AVPR2. Compared to the CG group, the CRF and CRF-CHF groups exhibited significantly elevated levels of 24 h urinary protein, SCr, BUN, and relative expression levels of AVPR1a and AVPR2 in the renal cortex and medulla. The CHF and CRF-CHF groups showed significant increases in LVEDP and LVW/BW (P < 0.05). Additionally, compared to the CG group, the other three groups had significantly increased urinary sodium and blood potassium levels, and significantly decreased urinary potassium and blood sodium levels (P < 0.05). Compared to the CRF and CHF groups, the CRF-CHF group exhibited significantly higher levels of 24 h urinary protein, SCr, BUN, and relative expression levels of AVPR1a and AVPR2 in the renal cortex and medulla, along with significantly increased LVEDP and LVW/BW, significantly reduced LVSP, significantly increased urinary sodium and blood potassium levels, and significantly decreased urinary potassium and blood sodium levels (P < 0.05). Rats with CRF-CHF experienced exacerbated renal and cardiac failure, characterized by significant disturbances in water and sodium metabolism and abnormal expression of AVPR1a and AVPR2.