Effects of sympathetic nerve stimulation on lung fluid and protein exchange

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Abstract
The effects of stellate ganglion stimulation (SGS) on lung fluid and protein exchange were studied in anesthetized sheep lung by monitoring the pulmonary lymph flow (.ovrhdot.Qlym) and lung lymph and plasma protein concentrations. SGS resulted in increases in .ovrhdot.Qlym and protein flow (.ovrhdot.Qlym .times. lymph protein concentration) that were independent of the pulmonary hemodynamic alterations, but were dependent on the stimulus strength. Baseline .ovrhdot.Qlym and protein flow of 4.21 .+-. 1.26 ml/h and 0.25 .+-. 0.11 g/h were increased to steady-state values of 6.17 .+-. 1.70 ml/h and 0.36 .+-. 0.15 g/h during 20 V SGS (P < 0.05) and to 8.77 .+-. 2.51 ml/h and 0.52 .+-. 0.21 g/h during 40 V SGS (P < 0.05). The effect of SGS on lymph and protein flows was reduced by pretreatment with phentolamine. Phentolamine baseline .ovrhdot.Qlym and protein flow of 5.31 .+-. 1.41 ml/h and 0.26 .+-. 0.10 g/h were increased to 5.85 .+-. 1.49 ml/h and 0.36 .+-. 0.12 g/h during 40 V SGS (P < 0.05). The increases in .ovrhdot.Qlym and protein flow in the phentolamine-treated animals were associated with increases in pulmonary artery pressure and blood flow and could be due to increased vascular surface area and microvascular pressure. The increases in .ovrhdot.Qlym and protein flow in the untreated animals cannot be explained totally by the hemodynamic changes. The increases in .ovrhdot.Qlym and protein flow during sustained sympathetic stimulation may be due to increase in the lung vascular permeability.