Figure 1.

Experimental protocol used to examine the influence of LPS on the electrically- or noradrenaline-induced increase in DBP in pithed and vagotomized rats. Each animal received an injection of pancuronium (0.8 μmol kg⁻¹). After 5 min, the first stimulus (S₁) was applied. DBP was increased by bolus injection of noradrenaline (1–3 nmol kg⁻¹) or by ES (1 Hz, 1 ms, 50 V for 10 s) of the preganglionic sympathetic nerve fibers. A single dose of LPS (0.4 or 4 mg kg⁻¹) or vehicle was slowly injected (over a time period of 1 min) 5 min after S₁. An infusion of vasopressin started 2 min before the administration of LPS. Stimulations (S₂–S₄) were repeated at intervals of 10 min following the administration of LPS or its vehicle. The effects of LPS or its vehicle were also examined after administration of clobenpropit (0.1 μmol kg⁻¹, given along with pancuronium), SR 141716A (0.03 or 0.1 μmol kg⁻¹) or SR 144528 (3 μmol kg⁻¹; each compound was given 5 min prior to pancuronium). Due to its short-lived effects, capsazepine (1 μmol kg⁻¹) was injected 2 min prior to S₁ and S₃.