Physiological alterations in the pulmonary capillary bed at rest and during exercise. The effect of body position and trimethaphan camphorsulfonate.

ume to or from the lung affect the pulmonary capillary blood volume (Vc) as measured with carbon monoxide diffusing techniques.'-5 However, the available information suggests that this mechanism is inadequate to explain the larger increases in diffusing capacity (DL,.O ) observed during exercise.1-6 Other concomitants of exercise which have been examined do not affect DL00.7' 8 The purpose of this study was twofold: (1) to examine the effects of altered gravitational influences on the exercise-induced increases in DL,O; and (2) to evaluate the role of the sympathetic nervous system in this phenomenon by studying the effects of exercise before and during infusions of trimethaphan camphorsulfonate (Arfonad).