Effects of aqueous extracts of Apocynum venetum leaves on spontaneously hypertensive, renal hypertensive and NaCl-fed-hypertensive rats

Effects of aqueous extracts of Apocynum venetum leaves (Luobuma extracts) on the blood pressure were evaluated in hypertensive animal models, such as spontaneously hypertensive rats (SHR), renal hypertensive rats and NaCl-induced hypertensive rats. In SHR, administration of Luobuma (heat-processed and unprocessed leaves) extracts at a dose of 70 mg/rat per day significantly decreased the systolic blood pressure value, but their decreasing effects were weaker than that of captopril. The urine volume, and the urinary Na(+), K(+) and protein excretions were not significantly different between Luobuma-treated and untreated groups. In 3/4 nephrectomized rats, the Luobuma extracts significantly decreased the systolic blood pressure value, accompanied by significant increases of the urine volume and the urinary Na(+) and K(+) excretions. Furthermore, they decreased the blood urea nitrogen (BUN) level. In NaCl-induced hypertensive rats, the Luobuma extract decreased the systolic blood pressure value. However, it did not change the urinary excretions of Na(+), K(+) and protein. The BUN level was lower than that of control rats, but the serum total cholesterol (TC) level did not changed. From these findings, the Luobuma extracts have an anti-hypertensive effect, possibly due to amelioration of the kidney functions in the three experimental animal models.