Effects of intravenous atropine on static P-V curves of the lung in normal man.
In eight normal subjects we studied the effects of intravenous (i.v.) injection of 2 mg atropine sulfate on the static lung recoil pressure-volume (PV) curves, plethysmographic airway resistance (Raw), and maximum expiratory flow rates (Vmax). In addition, we determined the influence of atropine injection in esophageal elastance (Ees) by measuring the esophageal pressure with an esophageal balloon containing five different volumes (0.5 to 4 ml) of air and by calculating the change in esophageal pressure per unit change in balloon volume (delta Pes/delta Vb). This procedure allowed us to obtain static lung recoil pressure (Pst(1] at a balloon volume extrapolated to zero, thus avoiding the interference of changes in esophageal tone following atropine administration with the measurement of Pst(1). After vagal blockade with atropine, Pst(1) significantly decreased with a shift to the left of PV curves, Raw decreased, and Vmax increased mainly at lower lung volumes. Ees also decreased with parasympathetic blockade. We interpret these findings to indicate that inhibition of vagal tone results in dilatation of large and small airways, and also in the relaxation of smooth muscle in terminal lung units.
Terra-Filho
J
J
Department of Medicine, School of Medicine of Ribeirão Preto, University of São Paulo, Brazil.
Manço
J C
JC
Gallo L Júnior
Marin-Neto
J A
JA
Maciel
B C
BC
D000328:Adult; D000403:Airway Resistance / Q000187:drug effects*; D001285:Atropine / Q000494:pharmacology*; D004947:Esophagus / Q000187:drug effects; D006801:Humans; D007275:Injections, Intravenous; D008170:Lung Compliance / Q000187:drug effects*; D008297:Male; D011312:Pressure; D014630:Vagus Nerve / Q000187:drug effects
D001285:Atropine