title: Lung-deflating ability of rib cage and abdominal muscles in rabbits.
abstract: Anesthetized, apneic, mechanically ventilated rabbits were placed into a tilting plethysmograph that a rubber diaphragm, tightly fitting the animal's body just below the xiphoid process, separated into a rib cage and abdominal chamber. Expired volumes (DeltaV) and abdominal pressure changes (DeltaPab) were assessed in supine and upright posture during maximal rib cage (RCC) and/or abdominal compression (ABC) by pressurizing either or both chambers, and during maximal stimulations of abdominal muscles (ABS). With RCC, DeltaV supine and upright amounted to 16+/-4.9 (mean+/-S.D.) and 20.9+/-7% of the vital capacity in supine posture (VCs) and to 75.8+/-14.5 and 44.8+/-13.9% of the expiratory reserve volume (ERV) in corresponding posture, DeltaPab being negligible. With ABC, DeltaV was 13.7+/-2 and 38.9+/-7.3% VCs and 68.4+/-14.8 and 84.4+/-10.5% ERV, respectively. Both DeltaV and DeltaPab were similar with ABC and ABS, independent of posture. If this applies also to RCC and expiratory rib cage muscle contraction, maximal expiratory effects of the latter (a) are larger in upright than supine posture; (b) contribute to ERV more in supine than upright posture; and (c) are similar to those caused by ABS in supine, but substantially smaller in upright posture.
authors.affiliation: Istituto di Fisiologia Umana I, Università degli Studi di Milano, via Mangiagalli 32, 20133, Milan, Italy. edgardo.dangelo@unimi.it
authors.forename: Edgardo
authors.initials: E
authors.lastname: D'Angelo
authors.forename: Edi
authors.initials: E
authors.lastname: Prandi
authors.forename: Emanuela
authors.initials: E
authors.lastname: D'Angelo
authors.forename: Matteo
authors.initials: M
authors.lastname: Pecchiari
mesh_terms: D000009:Abdominal Muscles / Q000502:physiology*; D000818:Animals; D004558:Electric Stimulation; D005105:Expiratory Reserve Volume / Q000502:physiology; D008176:Lung Volume Measurements; D009119:Muscle Contraction / Q000502:physiology; D010991:Plethysmography; D011187:Posture / Q000502:physiology*; D011312:Pressure; D012123:Pulmonary Ventilation / Q000502:physiology*; D011817:Rabbits; D012272:Ribs / Q000502:physiology*