A possible mechanism of action of a new potassium channel opener, AL0671, on lipid metabolism in obese Zucker rats.

Antihypertensive drugs are expected to have a lipid-lowering effect for use in treating ischemic heart disease. We evaluated the effect of (+)-N-(6-amino-3-pyridil)-N'-[(1S,2R,4R)-bicyclo-[2.2.1]hept-2-yl] -N"- cyanoguanidine hydrochloride (AL0671), a newly synthesized cyanoguanidine-derivative potassium channel opener, on serum lipid and lipoprotein levels in obese Zucker rats, a genetically engineered model of type IV hyperlipidemia. AL0671 dose-dependently decreased systolic blood pressure in obese Zucker rats. Serial administration (for 1 or 2 weeks) of AL0671 (5 mg/kg/day) significantly decreased serum total triglyceride, chylomicron and very-low-density lipoprotein levels with increasing high-density lipoprotein cholesterol, whereas low-density lipoprotein levels did not change. AL0671 (5 mg/kg/day) increased lipoprotein lipase activities 4-fold and hepatic triglyceride lipase activities 3-fold in postheparin plasma. Another urea-derivative compound, AL0674, whose potassium channel-opening activity is diminished, did not affect serum lipid and lipoprotein levels. These results suggested that AL0671 activates both lipoprotein lipase and hepatic triglyceride lipase activities through its potassium channel-opening activity followed by decreasing triglyceride-rich lipoproteins in genetically obese hyperlipemic rats. Therefore, AL0671 might be beneficial in the treatment of hypertensive patients with hypertriglyceridemia (probably with insulin resistance).