Magnesium lithospermate B ameliorates renal cortical microperfusion in rats

Aim: To investigate the effects of magnesium lithospermate B (MLB) isolated from Salviae miltiorrhizae on renal microcirculation, and renal and systemic hemodynamics in Sprague-Dawley rats. Methods: MLB (10, 30, and 60 mg/kg) was injected intravenously and renal blood flow (RBF), renal cortical microperfusion (RCM), and systemic hemodynamic function parameters including heart rate (HR), mean arterial pressure (MAP), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), and maximal velocity of pressure increase (dp/dt(max)) were measured for 45 min after administration. Results: Intravenous MLB at doses of 10, 30, and 60 mg/kg increased RCM significantly, but had no obvious effects on RBF or systemic hemodynamics. The effect of MLB on RCM reached its peak 15 min after injection and returned to baseline after 45 min. Up to 60 mg/kg MLB increased RCM by 62.4%+/- 20.2% (changes from baseline, P < 0.01), whereas RBF (3.7%+/- 9.7% vs baseline) and renal vascular resistance (-1.4%+/- 9.1% vs baseline) did not obviously change. Conclusion: These results indicate that MLB ameliorates renal microcirculation in a dose-dependent manner, which may be related to the renoprotective effects of MLB.