|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1998 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1997 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1996 : ¥1,100,000 (Direct Cost : ¥1,100,000)
This study was designed to evaluate the role of the autonomic nervous system and cytokines in anaphylactic hypotension in urethane-anesthetized rabbits. Forty rabbits, which were sensitized by canine serum, were divided into the following four groups : animals with neuraxis intact (INTACT group, N=10), those with cervical vagotomy (VAGOTOMY group, N=10), those with the carotid sinus and aortic nerves denervation (SAD group, N=10) and those with SAD plus cervical vagotomy (SADV group, N=10). They were challenged to induce anaphylactic hypotension by canine serum injection. Other ten rabbits treated with SADV, also sensitized by the serum, were challenged with the serum into the fourth ventricle of the brain. Mean blood pressure (MBP), central venous pressure (GVP), heart rate (HR) and renal nerve activity (RNA) were measured. In the INTACT group, no changes in RNA and HR occurred after injection even on systemic hypotension associated with CVP elevation In the VAGOTOMY group, however, an augmented RNA developed with a MBP drop after the injection. In the SAD group, both RNA and HR during anaphylactic hypotension decreased profoundly. The intrathecal injection of serum, the dose of which should not produce hypotension if given systemically, caused systemic hypotension associated with RNA decline. Cytokines changes (IL-6 and IL-8) in the INTACT group were not significant due to large deviations of the data, suggesting differences in the degree of the sensitization each animal. These results support and strengthen our previous data that in the rabbits, sympathetic nerve responses to anaphylactic hypotensionis modified by inputs via the cervical vagal nerves. Hypotension arid sympathetic depression during anaphylactic shock, may be overridden by a sympathetic inhibition through the central
nervous system. Cytokine changes during anaphylactic shock is required to define further in an experimental model which allows to standardized the sensitization in each animal.