Yasuhiro Teranishi (1), Tsutomu Kumazaki (2), Ryoji Ozono (3) and Hiromichi
Tsuru (4)
(1) Department of Physiology, (2) Department of Biochemistry and Biophysics,
Research Institute for Radiation Biology and Medicine, (3) Department of
Clinical Laboratory Medicine, Hiroshima University School of Medicine, Minami-ku,
Hiroshima 734-8551, Japan
(4) Department of Pharmacology, Toho University School of Medicine, Ohta-ku,
Tokyo 143-8540, Japan
Abstract: The interaction between [Arg8]-vasopressin and
a vasopressin receptor antagonist, [d(CH2)51,
O-Me-Tyr2, Arg8]-vasopressin, was examined in Hiroshima
rats and normotensive control rats under pentobarbital anesthesia. [Arg8]-vasopressin
dose-dependently increased the arterial pressure in both the Hiroshima and
control rats, the pressor effect being greater in the Hiroshima rats. After
the administration of a vasopressin antagonist (0.01 mg/kg), which by itself
decreased arterial pressure only in the Hiroshima rats, the dose-response
curve for [Arg8]-vasopressin was much more greatly shifted to
the right in the control rats. These results indicate that with or without
a vasopressin antagonist, the exogenous [Arg8]-vasopressin induced
more powerful pressor actions in the Hiroshima rats compared to the control
rats.
Keywords: Vasopressin system, Vasopressin antagonist, Borderline-hypertensive
rat