Abstract
(6)-Shogaol-induced pressor responses in blood pressure of rats were studied. Intraventricular injection of (6)-shogaol (0.1 to 0.5 μg) caused a pressor response in a dosedependent manner. (6)-Shogaol (0.5 mg/kg, i. v.)-induced pressor response was markedly reduced by a spinal destruction to the sacral cord level. However, norepinephrine (10 μg/kg, i. v.)-induced pressor response was not affected by the spinal destruction. In rats in which the spinal cord was destroyed to the thoracic cord level, (6)-shogaol-induced pressor response was reduced by hexamethonium (10 mg/kg, i. v.) and phentolamine (10 mg/kg, i. v.), etc. When the spinal cord was destroyed to the sacral cord level, the pressor response was not affected by these blockades. In the hindquarters of rats which were perfused with rats'blood, (6)-shogaol caused two pressor responses on the perfusion pressure. The first pressor response, which was accompanied by a rise in systemic blood pressure, was reduced by hexamethonium but was not entirely eliminated by phentolamine. However, the pressor response disappeared with spinal destruction to the sacral cord level. The second pressor response, which occured about when the systemic blood pressure regained its original pressure, was not affected by hexamethonium, phentolamine or spinal destruction. Pressor response induced by the injection of (6)-shogaol (10 μg) into the perfusion circuit was not affected by phentolamine and spinal destruction. Furthermore, (6)-shogaol-induced peripheral pressor response disappeared with the combined treatment of [D-Arg1, D-Pro2, D-Trp7, 9, Leu11]-substance P (0.5 mg/kg, i. v.), phentolamine and the section of the sciatic nerves.
