Effects of rhynchophylline and isorhynchophylline on blood pressure and blood flow of organs in anesthetized dogs

In anesthetized thoracotomized dogs, rhynchophylline (Rhy 5 mg.kg-1, iv) reduced the mean arterial pressure (MAP), heart rate (HR), and coronary blood flow (CBF) by 1.16 +/- s 0.67 kPa, 19 +/- 12 beats/min, and 0.12 +/- 0.04 ml.min-1.g-1, whereas isorhynchophylline (Isorhy 1 mg.kg-1, iv) reduced the parameters by 3.58 +/- 0.19 kPa, 26 +/- 18 beats/min, and 0.10 +/- 0.04 ml.min-1.g-1, respectively. In unthoracotomized dogs, Rhy (10 mg.kg-1, iv) decreased renal blood flow (RBF) by 0.35 +/- 0.16 ml.min-1.g-1, but did not change the MAP. Isorhy (5 mg.kg-1, iv) reduced the MAP by 3.44 +/- 1.44 kPa, but the RBF remained unaffected. These results indicated that the hypotensive effect of Isorhy in a dosage not affecting RBF was more potent than that of Rhy.