Septic shock has a high mortality rate due to the hypotension and circulatory disorder that occurs during its pathogenesis. Recently, humoral factors such as cytokines and nitric oxide became important in the complex pathophysiology of septic shock because there is a close relationship between the determined levels of these humoral factors and the responses to the therapy and survival periods. Verapamil and nifedipine are calcium channel blockers commonly used in the pharmacotherapy of cardiovascular disorders. In the present study these drugs were investigated in the rat septic shock model. In vivo hemodynamic parameters were recorded using a data acquisition system in endotoxin-induced septic shock in rats. The animals were followed for 5h and blood pressure, rectal temperature, and ECG were recorded. Blood samples were collected at 1h and 5h time points after the injection of endotoxin, and serological samples were stored at -25 degrees C. Subsequently, tumor necrosis factor-alpha, interleukin-10 (enzyme-linked immunosorbent assay), and nitrite (Griess reagent) were determined in these serological samples. Significant correlations were observed between these humoral factors and the disordered hemodynamic factors. A reversal of changes was observed in the levels of serum cytokines, nitrite levels, and hemodynamic parameters with verapamil and nifedipine preadministration (P < 0.05). Additionally, superoxide dismutase (SOD), catalase, and malondialdehyde (MDA) were determined in livers obtained from these animals at the end of the experiments, and these results were compared to hemodynamic parameters and cytokines. Nifedipine and verapamil increased the levels of MDA and SOD but did not change catalase activity.