Pulmonary Effects of Prolonged Sympathetic Stimulation

Abstract

Previous clinical studies (1-3) have shown that the sympathetics play a major role in the development of acute pulmonary injury associated with mechanical CNS damage, surgical trauma, and severe nonspecific stress. Similar fi'ndi'ngs in animals exposed to experimental head injury (4-7), hyperbaric oxygen (8), and sympathetic nerve stimulation suggest that, in addition to possible hemodynamic changes, the sympathetics may alter the alveolar surfactants prior to the subsequent development of pulmonary congestion and edema (9, 10). Previous work has shown that shortterm stimulation of the sympathetics results immediately in a decreased lung compliance and altered surfactants in the absence of any initial gross lung injury (lo), as evidenced by normal or even decreased lung wt/body wt ratios. In the present study, experiments were carried out in order to determine what effect prolonged continuous sympathetic nerve stimulation in cats might have on lung compliance and lung wtlbody wt ratios.Methods. Fifteen adult cats were anesthetized with ketamine (30 mg/kg, im), the femoral artery catheterized, and the right stellate ganglion isolated via a lateral incision while avoiding rupture of the thoracic pleura. Wire electrodes were attached to the ganglion and stimulation applied by a Grass S-7 stimulator (10 V, 0.5 msec, lO/sec, square wave). A vinyl esophageal balloon 2 in. long was inserted into the stomach and then retracted 2 in. so that it was located in the esophagus. The cat was then placed in a whole-body pressure plethysmograph which, after equilibration was established, was calibrated for the mea-1 Supported by the Detroit General Hospital Research Corporation and a UND Faculty Research Grant.suremen t of tidal volume. Periodic measurements of esophageal pressure and tidal volume were made prior to stimulation of the pulmonary sympathetics and for a 3 hr period during continuous stimulation. After such stimulation, the lungs were carefully excised, grossly examined, photographed, weighed, dried, the dry weight determined, and the lung wt/body wt and lung wt/dry wt ratios calculated.Results. The results from the present study show that continuous sympathetic nerve stimulation results in an initial 38% compliance decrease which persists for at least 3 hr. Such a compliance decrease occurs in the absence of gross pulmonary congestion and edema. In 15 cats exposed to sympathetic stimulation the control lung compliance based on tidal volume and esophageal pressure at points of zero airflow was 0.037 -C-0.005 (SE) liter/cm HzO compared to 0.023 * 0.004 immediately after stimulation, P < 0.05. Lung wt/body wt ratios increased only 4% in 11 stimulated cats, 0.0072 * 0.001 compared to four normal controls, 0.0069 * 0.003, showing no significant change. Furthermore, there was no significant change in lung wet wt/dry wt ratios. Three control values were 4.46 * 0.12 compared to 4.44 t 0.06 for 11 stimulated cats. There was little or no evidence of gross hemorrhage or edema in any of the cat lungs.Discussion. Previous work s...

Physical Properties and Biochemistry of Lung Surfactant Following Vagotomy

“…The deleterious sympathetic influence on the surface activity has been found by Beck man et al [1971] and Droste and Beckman [1974]. These authors have come to the conclusions that exaggerated sympathetic tonus can change the surfactant before pul monary congestion and edema develops.…”