Alteration in diaphragmatic function induced by acute necrotizing pancreatitis in a rodent model.

Some of the common complications of acute necrotizing pancreatitis also involve pulmonary complications. These manifestations are often associated with a cephalad diaphragmatic shift. We hypothized that diaphragmatic function might be directly compromised by the acute abdominal process.

Diaphragmatic function is markedly altered in cerulein-induced pancreatitis.

Objective: To assess diaphragmatic function in vitro during experimental cerulein-induced acute pancreatitis.

Design: Prospective, randomized, controlled animal trial.

Setting: Research laboratory at a large university medical center.

Calcium ATPase and respiratory muscle function.

The sarcoplasmic reticulum (SR) of striated muscle is a highly specialized intracellular membrane system that plays a key role in the contraction-relaxation cycle of muscle. Its primary function is the regulation of cytoplasmic Ca2+ concentration. A key element in this regulation is the Sarco(endo)plasmic reticulum Ca2+-adenosine triphosphatase (SERCA), which by sequestering Ca2+ into the SR, induces and maintains relaxation.

Effects of corticosteroids on epithelial structure and smooth muscle function of rat trachea.

Corticosteroids, efficient drugs for the treatment of severe asthma, may have numerous side effects. We investigated the effects of 7 days of treatment with triamcinolone (1.2 mg x kg(-1) x day(-1)) on the epithelial structure, tracheal smooth muscle cross-sectional area and contractility in the rat.

Effects of mechanical ventilation on diaphragmatic contractile properties in rats.

We measured in rats the effects of 48 h of mechanical ventilation on the weight, contractile properties, and enzymatic profile of the diaphragm, the soleus and the extensor digitorium longus (EDL) muscles. Eighteen animals were randomly divided into a mechanically ventilated (MV, n = 9) group or a control (C, n = 9) group. During the 48 h of mechanical ventilation, animals in the MV group were anesthetized with sodium thiopental and enterally fed with a gastric catheter.

Effect of steroids on diaphragm of newborn, weanling adolescent, and adult rats.

The purpose of this study was to compare the effects of dexamethasone on the rat diaphragm during the postnatal period and into adulthood. Groups of 48 newborn, 60 weanling adolescent, and 60 adult rats were either (1) treated with DXM (ST, steroid-treated animals) or (2) untreated and pair-fed (C, control animals). After birth, 24 newborn rats were kept with their mother, which received a daily intramuscular injection of 0.

In vitro functions of the rat diaphragm during postnatal development.

This study was designed to determine the developmental changes in the functional characteristics of the rat diaphragm. A total of 150 animals were studied at 1, 3, 5, 7 and 9 weeks of postnatal age. Body and diaphragm muscle weights were measured.

Multiple effects of BAY K 8644 and nifedipine on isolated diaphragmatic fibers in vitro.

The dose-response effects of BAY K 8644 and nifedipine on diaphragmatic contractility were assessed in vitro. Isolated diaphragmatic fibers were obtained from rats and placed in an open-topped channel of a Plexiglas tissue chamber perfused with continuously flowing Krebs solution heated to 37 degrees C. Isometric twitch force, generated in response to 1-Hz supramaximal electrical stimulation (4 times/min), was measured with a highly sensitive photoelectric force transducer.

Expiratory flushing of airways: a method to reduce deadspace ventilation.

A jet of fresh gas entering the trachea during the last part of expiration, expiratory flushing of airways (EFA), may during mechanical ventilation bring the fresh gas interface into the trachea to reduce deadspace. EFA, delivered in a variety of modes, was tested in healthy dogs. EFA allowed tidal volume, peak and mean airway pressure to be reduced by about 25%.

Effects of steroids on diaphragmatic function in rats.

The present study was undertaken to determine the effects of 8 days of corticosteroid administration on diaphragmatic atrophy and contractile properties. One hundred sixty rats were divided into a pair-fed (PF) group (n = 80) and a steroid-treated (ST) group (n = 80). The treated rats received a single injection of Kenacort 80 retard (0.

Acute diaphragmatic changes induced by starvation in rats.

The aim of this study was to assess in an in vivo rat model the effects of total starvation for 4 d on diaphragmatic strength and endurance. Twenty-four rats were divided equally into a control (CTL) group and a starved (ST) group. Diaphragmatic strength was assessed and endurance index was calculated.

Effects of isoflurane on contractile properties of diaphragm.

Isoflurane has been shown to depress skeletal muscle force in vitro, but data are not available regarding the effects of isoflurane on diaphragmatic muscle function in vivo. To answer this question, 15 rats anesthetized with pentobarbital and mechanically ventilated were studied. They were divided into three groups of five animals each, according to the administered concentration of isoflurane.

Effects of Ca2+ withdrawal on diaphragmatic fiber tension generation.

The effects of extracellular Ca2+ withdrawal were studied on isolated diaphragmatic muscle fibers and compared with the effects on the papillary, soleus, and extensor digitorum longus (EDL) contractility, using the same in vitro model. Diaphragmatic fibers were obtained from 15 rats, and papillary muscles, soleus, and EDL were obtained from 10 animals. Isometric force generated in response to 1-Hz supramaximal electrical stimulation was measured with a highly sensitive photoelectric transducer.

Effects of phrenic nerve cooling on diaphragmatic function.

The effects of phrenic nerve cooling at 0 degrees C on the nerve and diaphragmatic function were evaluated in dogs. Eleven dogs, anesthetized and mechanically ventilated, were studied. Left diaphragmatic function was assessed by recording the transdiaphragmatic pressure (Pdi) generated during electrical stimulation of the left phrenic nerve at different frequencies (0.

Different effects of halothane on diaphragm and hindlimb muscle in rats.

The effects of halothane administration on diaphragm and tibialis anterior (TA) muscle were investigated in 30 anesthetized mechanically ventilated rats. Diaphragmatic strength was assessed in 17 rats by measuring the abdominal pressure (Pab) generated during supramaximal stimulation of the intramuscular phrenic nerve endings at frequencies of 0.5, 30, and 100 Hz.

Effects of theophylline and enprofylline on diaphragmatic contractility.

Experimental data suggest that theophylline (T) enhances diaphragmatic contractility by increasing the influx of calcium at the cell membrane level through an inhibition of adenosine receptors (Aubier et al., J. Appl.

Effects of digoxin on diaphragmatic strength generation in patients with chronic obstructive pulmonary disease during acute respiratory failure.

We studied the effects of digoxin, a compound that has an inotropic effect on the myocardium, on diaphragmatic function in 8 patients with chronic obstructive pulmonary disease. All the patients were in acute respiratory failure and were artificially ventilated. Diaphragmatic strength was assessed by measuring the transdiaphragmatic pressure generated at functional residual capacity during bilateral supramaximal electrical stimulation of the phrenic nerves.

Diaphragmatic contractility after upper abdominal surgery.

Postoperative dysfunction of the diaphragm has been reported after upper abdominal surgery. This study was designed to determine whether an impairment in diaphragmatic contractility was involved in the genesis of the diaphragmatic dysfunction observed after upper abdominal surgery. Five patients undergoing upper abdominal surgery were studied.

Effects of digoxin on diaphragmatic strength generation.

Contrary to hindlimb muscle, extracellular calcium plays an important role in diaphragmatic strength generation (J. Appl. Physiol.

Effects of theophylline on isolated diaphragmatic fibers. A model for pharmacologic studies on diaphragmatic contractility.

An in vitro model of isolated diaphragmatic muscle fibers was developed to study the effects of theophylline on diaphragmatic contractility. The effects of theophylline on this model were compared for each dose with the effects of the drugs on a "classic" hemidiaphragmatic muscle preparation. Diaphragmatic strips obtained from 20 rats were placed into an open topped channel of a plexiglass tissue chamber and perfused with continuously flowing Krebs solution heated to 37 degrees and bubbled with a 95% O2 and 5% CO2 gas mixture so as to maintain pH, PO2, PCO2 constant (7.

Effect of halothane on diaphragmatic muscle function in pentobarbital-anesthetized dogs.

The mechanism underlying the decrease in minute ventilation (VE) observed under halothane anesthesia was investigated in nine spontaneously breathing dogs. Anesthesia was induced with pentobarbital sodium and was maintained with halothane. Inspired fraction of halothane (FIhal) was increased every 30 min, from 0.

Effect of hypophosphatemia on diaphragmatic contractility in patients with acute respiratory failure.

We studied the effects of hypophosphatemia on diaphragmatic function in eight patients with acute respiratory failure who were artificially ventilated. Their mean serum phosphorus level was 0.55 +/- 0.

Effects of hypocalcemia on diaphragmatic strength generation.

We studied the effects of hypocalcemia on diaphragmatic force and diaphragm blood flow (Qdi) in 12 anesthetized dogs. The diaphragm was electrically stimulated with intramuscular electrodes surgically implanted in the ventral surface of each hemidiaphragm. The transdiaphragmatic pressure (Pdi) during supramaximal (50 V) 2-s stimulations applied over a frequency range of 10-100 Hz was measured with balloon catheters during tracheal occlusion at functional residual capacity.

Bilateral phrenic stimulation: a simple technique to assess diaphragmatic fatigue in humans.

Transdiaphragmatic pressure (Pdi) and the rate of relaxation of the diaphragm (tau) were measured at functional residual capacity (FRC) in six normal seated subjects during single-twitch stimulation of both phrenic nerves. The latter were stimulated supramaximally with needle electrodes with square-wave impulses of 0.1-ms duration at 1 Hz before and after diaphragmatic fatigue produced by resistive loaded breathing.