Urapidil in Normotensive and Spontaneously Hypertensive Rats: The Effects on Systemic and Regional Haemodynamics and Cardiac Mass

The effects of treatment for three weeks with urapidil (10 mg/kg p.o. twice daily) on systemic and regional haemodynamics and cardiac mass were studied in normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Urapidil decreased mean arterial pressure and total peripheral resistance index (176 ± 3 versus 145 ± 5 mmHg and 0.61 ± 0.02 versus 0.49 ± 0.02 units, respectively; each P < 0.01) in SHR without affecting heart rate, cardiac index or cardiac mass. No systemic haemodynamic changes were observed in WKY rats. All organ vascular resistances decreased significantly in SHR and blood flow increased to skin (P < 0.01) and kidneys (P < 0.05). These data indicate that urapidil is a potent antihypertensive agent in SHR which reduced mean arterial pressure through a decreased total peripheral resistance that was distributed throughout all circulations. Despite these haemodynamic changes, cardiac mass did not change.