Hypotensive and vasodilator effects of triacetonamine as demonstrated by intravital microcirculation method

Triacetonamine was isolated from the South China Sea gorgonian Juncella squmata. The hypotensive and microvascular vasodilator effects of triacetonamine were tested in ♂ Sprague-Dawley rats anaesthetized with Na pentobarbital (40 mg/kg, ip). Systemic arterial pressure was continuously monitored by a catheter in the carotid artery. The spinotrapezius muscle was exteriorized and its microcirculation was observed by an intravital video microscope system. The diameter of an arteriole (25-40 μm) in the spinotrapezius microcirculation was continuously and automatically measured by a dynamic video diameter analyzer. Triacetonamine was given either systemically (0.1-3 mg/kg, iv) or topically (0.5 μg-0.5mg/ml, suffused at 2 ml/min). Results showed that triacetonamine administered iv lowered arterial pressure and dilated arteriole in a dose-dependent manner, but it did not dilate the arterioles for direct topical application. The observed vasodilatation may result from inhibition of the vasomotor tone of the peripheral circulation by triacetonamine, thus leading to the concomitant decrease of peripheral resistance and hypotensive effect.