[Determination of plasma catecholamine as a quantitative index for the evaluation of sympathetic nervous system...

For many years blood pressure has been only an index among a number of physiological conditions presenting sympathetic nervous systems activities in methacholine test due largely to the lack of specific and practical method for the determination of catecholamine. We found that methacholine induced a significant increase in plasma catecholamines with an alternation in hemodynamic change in the present study by the use of high speed liquid chromatography and automated THI method. The increments in plasma catecholamines were not correlated with apparent decrements in blood pressure. Therefore the increments in plasma catecholamines induced by methacholine were not attributable to reflex responses to hemodynamic changes and rather could be the direct effect of methacholine on sympathetic neuron and adrenal medullae. Besides there was no correlation between the increments in plasma catecholamines and methacholine indices. These data question the suitability of blood pressure as an index for the evaluation of sympathetic nervous system function during methacholine test and suggest that plasma catecholamines might be a proper parameter for the sympathetic nervous activities response to methacholine.