The acute pressor response to cadmium in rats

In rats, acute i.v. administration of CdCl2 (0.5 and 1 mg/kg) produced a depressor response followed by a pressor response, while the acute i.p. administration of CdCl2 (0.5 and 1 mg/kg) produced only a pressor response. Phentolamine (5 mg/kg, i.v.), hexamethonium (10 mg/kg, i.v.), propranolol (2 mg/kg, i.v.) and indomethacin (20 mg/kg, i.p.) as well as bilateral adrenalectomy, acute reserpinization and chemical sympathectomy by guanethidine did not modify the acute pressor response to CdCl2. Verapamil (1 mg and 2 mg/kg, i.v.) and nifedipine (0.25 and 0.5 mg/kg, i.v.) prevented the acute pressor response to CdCl2 administered by either i.v. or i.p. route. Phentolamine (10 micrograms/ml) could not prevent the rise in perfusion pressure of the rat hindquarter due to intra-arterial CdCl2 administration. However, verapamil (50 and 100 micrograms/ml) prevented rise in perfusion pressure. It is concluded that cadmium ion might mimic calcium ion and produce a direct contractile effect on the vascular smooth muscle.