Effects of p chlorophenylalanine on blood pressure and heart rate in normal rabbits and rabbits with neurogenic hypertension

SUMMARY 1. Intraperitoneal administration of p‐chlorophenylalanine (pCPA: 100–400 mg/kg per day) reduced central serotonin concentrations to 20–50% of control in the rabbit. 2. Intraperitoneal administration of a single dose of pCPA (400 mg/kg) decreased heart rate by 14% for a period of 1–2 days, but did not affect arterial pressure. 3. Repeated intraperitoneal administration of pCPA (100 mg/kg per day) caused a gradual reduction in arterial pressure to about 90% of control values over a 10 day period, but had no consistent effect on heart rate. 4. In rabbits that received repeated intraperitoneal injections of pCPA (100 mg/kg per day), the tachycardia that followed sinoaortic denervation was not as well sustained as in normal rabbits; the development of neurogenic hypertension was unaltered. 5. Intracisternal administration of pCPA was particularly toxic in the rabbit; the maximum doses tolerated did not succeed in lowering central serotonin concentration and had no effect on blood pressure or heart rate.