Determination of rhynchophylline and isorhynchophylline in Uncaria rhynchophylla by HPLC Analysis on rhynchophylline in Uncaria macrophylla from different habitats in Guangxi at various periods Effects of Isorhynchophylline on Physiological Characteristics of Isolated Guinea Pig Atrium The Negative Chronotropic Effect of Isorhynchophylline and Its Mechanism Different Hypotentive Effects of Various Active Constituents Isolated from Uncaria rhynchophylla Analysis on rhynchophylline in Uncaria macrophylla from different habitats in Guangxi at various periods Antihypertensive effect and vascular regulation mechanism of rhynchophylline on spontaneously hypertensive rats