Control of catecholamine release and blood pressure with octreotide in a patient with pheochromocytoma: A case report with in vitro studies

A 65-year-old male patient with pheochromocytoma, whose hypertensive episod es were uncontrolled using conventional therapy, was successfully treated w ith octreotide (SMS 201-995). The serum catecholamine level and the urinary excretion of catecholamines decreased after 300 mu g/day of octreotide was administered. To clarify the mechanisms of octreotide that lower catechola mine released from a tumor, we studied the in vitro effects of octreotide o n membrane potentials and voltage-dependent Ca2+ channel (VDCC) current usi ng the whole-cell patch-clamp technique in single pheochromocytoma cells di spersed after tumor resection. The action potentials were reversibly inhibi ted with 10 mu M octreotide. In addition, the VDCC current evoked by depola rized pulses from the holding potential of -60 mV was inhibited with 10 mu M octreotide. Octreotide is useful for controlling blood pressure before su rgery in some patients with uncontrolled hypertension caused by a pheochrom ocytoma. Copyright (C) 2000 S. Karger AG, Basel.