Lung mechanics following antigen challenge of Ascaris suum-sensitive rhesus monkeys

Pulmonary resistance (RL) breathing air and a helium-oxygen mixture (He-O2) dynamic compliance (Cdyn), respiratory frequency (f), subdivisions of lung volume, and static deflation pressure-volume (PV) curves were measured before and after bronchial challenge with Ascaris suum antigen in six rhesus monkeys with varying skin reactivity to this antigen. The animals were lightly anesthetized with pentobarbital sodium, intubated, and studied in a volume displacement body plethysmograph, transpulmonary pressure being measured with an esophageal balloon technique. With the animals breathing spontaneously antigen was delivered with a De Vilbiss ultrasonic nebulizer and RL was determined by the method of electrical subtraction. With challenge, three monkeys showed no response and three persistently demonstrated significant bronchonconstriction (peak RL 700+/-100% control) with a decreased response to He-O2 suggesting combined central and peripheral airway narrowing. Responding monkeys also developed tachypnea (f 210+/-8% control) and a fall in Cdyn (18+/-6% control) but no significant changes in total lung capacity and its subdivisions, or in static PV curves were seen. We conclude that this primate model shows important similarities to and differences from human asthma.