抄録
The hemodynamic mechanism for anaphylactic shock is not fully clarified. We determined the change in peripheral vascular resistances during anaphylactic hypotension in anesthetized rats. We measured the mean circulatory filling pressure (Pmcf) using the mechanical occlusion method of inflation of the right atrial balloon, along with systemic arterial pressure (Psa), central venous pressure (Pcv) and portal venous pressure (Ppv). Cardiac output (CO) was also measured with the thermodilution method. From these hemodynamic variables we calculated the total peripheral (Rt) and venous (Rv) resistances during anaphylactic hypotension in anesthetized rats. These hemodynamic variables were compared with those in the hemorrhagic shock. After an intravenous injection of antigen ovalbumin 0.6mg in sensitized rats, Psa decreased from 119±4 to 43±2 mmHg, CO decreased from 84.5±5.7 to 37.8±2.1 ml min−1, Pcv decreased from 0.9±0.1 to 0.1±0.1 mmHg, and Pmcf also decreased from 6.0±0.2 to 5.2±.3 mmHg. Thus, the venous resistance (Rv) increased from 0.06±0.05 to 0.15±0.02 mmHg ml−1 min, but Rt did not significantly change. Ppv also increased from 5.6±0.5 to 21.5±0.9 mmHg. During hemorrhagic shock Psa decreased in the manner similar to anaphylactic shock; however, Rv did not significantly change and Ppv decreased. In conclusion, in rat anaphylactic shock, a substantial increase in Rv presumably due to hepatic venoconstriction may decrease venous return, resulting in systemic hypotension. [J Physiol Sci. 2008;58 Suppl:S182]
