alpha-Adrenergic blocking action of 1-O-hexadecyl-2-O-acetyl-sn-glycero-3-phosphocholine in rats.

The effect of 1-O-hexadecyl-2-O-acetyl-sn-glycero-3-phosphocholine (HAGPC), a major component of antihypertensive polar renomedullary lipid, on the pressor responses to norepinephrine and angiotensin II was investigated in normal Wistar rats. The pressor activity of norepinephrine (1 microgram/kg of body weight (BW)) and angiotensin II (40 ng/kg BW) were markedly suppressed when these substances were injected immediately after intravenous administration of 80 nmol/kg BW of HAGPC. When HAGPC was infused continuously at a rate of 20 nmol/kg BW/min, pressor responses to bolus injection of graded doses (0.5 to 10 micrograms/kg BW) of norepinephrine were significantly lowered, but pressor responses to 10 to 200 ng/kg BW of angiotensin II were not affected. These observations suggest that HAGPC has alpha-adrenergic blocking activity and does not influence angiotensin II receptors.