Vasopressin tachyphylaxis. A study in conscious man.

The effects of repeated intravenous constant infusion of lysine-8-vasopressin (LVP) in a series of 12 conscious patients with portal venous catheters were studied. The portal venous pressure fell, the arterio-portal venous oxygen difference and the systolic and diastolic blood pressures rose and the heart rate decreased. Although no signs of tachyphylaxis were seen in portal venous pressure, systolic blood pressure or heart rate, they were observed both in the arterio-portal venous oxygen difference, indicating a tachyphylactic reaction in the effects on splanchnic blood flow, and in the diastolic blood pressure.