Alpha-chloralose anesthesia inhibits the somato-sympathetic reflex response in cats more effectively than halothane.

The effect of halothane anesthesia (H; 0.8 Vol%) or alpha-chloralose anesthesia (AC; 60 mg/kg i.v.) on the somato-sympatho-adrenal reflex response evoked by supramaximal bilateral sciatic nerve stimulation, were examined in two groups of cats (H: n = 6; AC: n = 4). Blood samples were collected simultaneously from the adrenal vein and femoral artery at baseline (S1) and during bilateral sciatic nerve stimulation (S2) for the measurement of norepinephrine, epinephrine, neuropeptide Y, and Metenkephalin, while mean arterial blood pressure (MABP) and heart rate (HR) were recorded. There were no differences between groups at baseline. In halothane anesthetized cats, sciatic nerve stimulation caused significant increases in MABP (S1: 113 +/- 8 mm Hg, S2: 178 +/- 10 mm Hg; mean +/- SE), HR (S1: 223 +/- 15 bpm, S2: 278 +/- 22 bpm), and adrenal vein plasma levels of norepinephrine (S1: 3.1 +/- 0.98 ng/ml, S2: 19.53 +/- 11.5 ng/ml), epinephrine (S1: 15.5 +/- 4.76 ng/ml, S2: 67.31 +/- 14.9 ng/ml), neuropeptide Y (S1: 1.3 +/- 0.12 ng/ml, S2: 2.16 +/- 0.42 ng/ml), and Met-enkephalin (S1: 107 +/- 35.7 pg/ml, S2: 200 +/- 76.5 pg/ml). In contrast, sciatic nerve stimulation in alpha-chloralose anesthetized cats, caused a significant increase only in MABP during sciatic nerve stimulation (S1: 115 +/- 10 mm Hg, S2: 171 +/- 7 mm Hg), while HR and adrenal vein plasma levels of catecholamines, neuropeptide Y and Met-enkephalin remained unchanged from baseline. Adrenal vein epinephrine levels measured during stimulation in the alpha-chloralose group (S2: 6.17 +/- 0.86 ng/ml), were significantly lower as compared to values observed during halothane anesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)