Effects of SGB-1534, a new synthesized phenylpiperazine derivative, on blood pressure and heart rate in stroke-prone spontaneously hypertensive rats.

The present study was undertaken to elucidate the effects of a new synthesized phenylpiperazine derivative SGB-1534 on mean arterial blood pressure and heart rate in stroke-prone spontaneously hypertensive rats(SHRSP). SGB-1534 (0.05 and 0.5 mg/kg, i.v.) produced a significantly greater decrease in mean arterial blood pressure in SHRSP than in normotensive Wistar Kyoto rats(WKY). Heart rate also tended to decrease in parallel with the decrease in mean arterial blood pressure in SHRSP. In this study, it was revealed that SGB-1534 has an antihypertensive effect in SHRSP. An attempt was made to elucidate the hypotensive mechanism of SGB-1534 using WKY. SGB-1534 (0.5 mg/kg, i.v.) significantly inhibited pressor responses to norepinephrine (5 micrograms/kg, i.v.) and methoxamine (50 micrograms/kg, i.v.). SGB-1534 (0.5 mg/kg, i.v.) did not affect the preganglionic sympathetic adrenal nerve activity. The present findings suggest that the action site of SGB-1534 is not in the central nervous system, but in the peripheral alpha 1-adrenoceptors in rats.