Influence of tidal volume on histamine-induced bronchoconstriction in guinea pigs.
The effects of tidal volume amplitude on bronchopulmonary reactivity were investigated in three groups of 14 anesthetized paralyzed mechanically ventilated guinea pigs. Animals of group 1 served as control; in animals of group 2, both the sympathetic and parasympathetic nervous systems were blocked; in animals of group 3, only the parasympathetic system was blocked. In each group, the animals were randomly divided into two subgroups characterized by their ventilatory pattern: rate of 60/min with a 6-ml/kg tidal volume or rate of 40/min with a 9-ml/kg tidal volume. Bronchopulmonary reactivity to infused histamine was assessed by the respiratory compliance and conductance values measured during bronchoconstriction and expressed as a percentage of the corresponding basal values. In group 1 the animals ventilated with a 9-ml/kg tidal volume were found significantly less reactive than those ventilated with a 6-ml/kg tidal volume. This difference was abolished in groups 2 and 3. These results demonstrate that the effects of increased tidal volume on bronchopulmonary reactivity are vagally mediated and suggest that the decrease observed in histamine-induced bronchoconstriction is mainly due to reflex effects evoked by stretch receptor stimulation.
Benichou
M
M
Département de Physiologie, Institut National de la Santé et de la Recherche Médicale U296, Hôpital Henri Mondor, Creteil, France.
Lorino
A M
AM
Lorino
H
H
Macquin-Mavier
I
I
Istin
N
N
Harf
A
A
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001980:Bronchi / Q000503:physiopathology*; D003251:Constriction, Pathologic / Q000139:chemically induced; D006168:Guinea Pigs; D006632:Histamine; D008170:Lung Compliance; D008176:Lung Volume Measurements; D008297:Male; D011312:Pressure; D011433:Propranolol / Q000494:pharmacology; D012119:Respiration / Q000187:drug effects; D012121:Respiration, Artificial; D015656:Respiratory Mechanics / Q000187:drug effects; D013990:Tidal Volume
D001285:Atropine; D006632:Histamine; D011433:Propranolol