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Interferenza tra ossido d’azoto (NO) e canali del potassio ATP-sensibili sulla fatica diaframmatica nel suino
No full textIn 6 anaesthetized and mechanically ventilated Large White pigs we analyzed the interference between nitric oxide (NO) and K+ATP channels on diaphragmatic activity. The pigs were treated initially with NG-nitro-L-arginine methyl ester (L-NAME, 5 mg/kg i.v.), to block endogenous NO, and subsequently with Cromakalim (80 microg/kg i.v.) to open K+ATP channels. L-NAME increased systemic arterial pressure (PAM) and vascular resistances (RVS), while Cromakalim decreased both PAM and RVS. Cromakalim caused also an impairment of diaphragmatic activity, showing that when endogenous NO is blocked, also the K+ATP channels activity is altered
NO2 effects on the respiratory system of the pig, evaluated by rapid airway occlusion during constant-flow inflation
No full textEffects of PGF2alpha on the EMG of costal and crural parts of the diaphragm of the newborn pigs
No full textWe investigated the effects of PGF2 alpha on the breathing patterns and electric activity of costal and crural parts of the diaphragm in 9 anesthetized newborn pigs. The change in diaphragmatic tension was evaluated as the change in transdiaphragmatic pressure. Because PGF2 alpha induces bronchoconstriction and an increase in respiratory resistances, the changes induced by prostaglandin were evaluated as differences between bronchoconstriction after PGF2 alpha and resistive load obtained by applying gradual occlusion to the inspiratory line of the breathing circuit. Our results show that PGF2 alpha decreased respiratory frequency with lengthening of expiratory time, while the resistive load increased both respiratory phases. The changes in breathing pattern were associated with different electrical activities of the diaphragm. While resistive load did not significantly change the EMG power spectrum, PGF2 alpha recruited new motor units. Furthermore, resistive load induced synchronization of the inspiratory time discharge of the costal and crural parts of the diaphragm, while after PGF2 alpha infusion there was an early inspiratory discharge of the crural part
Valutazione nel suino dell'effetto indotto dalla SO2 e NO2 sulle proprietà elastiche e resistive del sistema respiratorio
No full text24 Large White pigs of 20±2 (D.S.) kg were used to study the effects of environmental pollutant gases NO2 and SO2 on viscoelastic characteristics of respiratory system. By the partition method it is possible to distinguish the tracheobronchial airways mechanic from the lung mechanic. The considered gases were administered at concentration of 50-100-200-400 ppm for NO2 and 50-100-500-700 ppm for SO2. The NO2 demonstrated to modify negatively the viscoelastic characteristics of the lung inducing a decrease of distensibility. The SO2 at higher concentrations exerts a lower effect than NO2
Effects of nitric oxide on diaphragmatic muscle endurance and strength in pigs
No full textThe aim of the study was to evaluate the effects of nitric oxide (NO) on diaphragmatic fatigue in fifteen anaesthetized, mechanically ventilated pigs, divided into three groups. The animals were pre-treated with indomethacin (3 mg kg-1, i.v.) to block the cyclo-oxygenase pathway. To group 1 pigs (n = 6) NG-nitro-L-arginine methyl ester (L-NAME, 5 mg kg-1 i.v.) was administered as a bolus to block endogenous NO production, while group 2 pigs (n = 6) were infused with sodium nitroprusside (SNP, 0.023 mg kg-1, i.v.), a donor of NO. Group 3 pigs (n = 3) were used as the controls. We evaluated diaphragmatic strength by measuring the transdiaphragmatic pressure (P di) generated during bilateral phrenic nerve stimulation at 10, 20, 30 and 50 Hz, 15 V, while the diaphragmatic endurance was assessed by a 30s stimulation at 10 Hz, 15 V. Diaphragmatic index was assessed as the ratio of peak force between single twitches performed before and after the 30 s stimulation west. We also evaluated mean systemic (MAP) and pulmonary (MPAP) arterial pressures, pulmonary wedge pressure (PW), systemic (SVR) and pulmonary vascular resistance (PVR) and cardiac output (CO). L-NAME increased MAP, MPAP, PW, SVR and PVR, but decreased CO. SNP caused a decrease in MAP, MPAP, PW and SVR, while PVR and CO did not change. The main finding of this study was that diaphragmatic strength was not significantly weakened after L-NAME administration, except at 10 Hz, while it did not change after SNP infusion. However, both L-NAME and SNP caused significant decreases in diaphragmatic endurance capacity. The fatigue appearing after L-NAME is probably correlated with a decline in diaphragmatic blood flow, as evidenced by the increase in SVR and the decrease in CO, and consequently in oxygen supply. In contrast, the decrease in endurance capacity after SNP infusion can be attributed to a direct action of NO on skeletal muscle
PGF2 and breathing pattern in newborn pigs
No full textThe effect of PGF2 alpha has been evaluated in 11 unanaesthetized unrestrained piglets and in 3 anaesthetized piglets (2-3 days old) using a barometric-plethysmographic technique. PGF2 alpha (mg 0.25/pig) was administered as aerosol for 5 min. In 3 of the unanaesthetized newborn pigs the effect of PGF2 alpha aerosol has been evaluated after indomethacin (mg 1/Kg i.v.). The vagal dependent activity of the prostaglandin was also evaluated after atropine (mg 0.08/Kg i.m.). Our results show that PGF2 alpha in newborn pigs causes hypoventilation due to a decrease in respiratory rate and to a lengthening in TE. The changes in TE are due to an increase in the incidence and duration of apneic events characterizing the respiratory activity at birth. After indomethacin PGF2 alpha does not change the breathing pattern. Atropine only partially reduces the effects of PGF2 alpha while, after anaesthesia, prostaglandin does not change the breathing pattern. Consequently our results show that PGF2 alpha in newborn animals similar to other prostaglandins acts as a depressant of respiratory activity
Globuli rossi a membrana modificata quale causa di microembolismo polmonare acuto nel suino
No full textEffects of vagotomy on respiratory mechanics in newborn and adult pigs
No full textWe have examined breathing patterns and respiratory mechanics in anesthetized tracheostomized newborn piglets and adult pigs and the changes determined by cervical bilateral vagotomy. Piglets had a respiratory system compliance and resistance, on a per kilogram basis, respectively, higher and smaller than the adults. After vagotomy neither variable changed in the newborn, but resistance dropped in the adult. This may suggest that efferent vagal control of bronchomotor tone is more pronounced in the adult. Respiratory system time constant was longer in newborns both before and after vagotomy. The distortion of the chest wall, examined as the ratio between the volume inhaled spontaneously and the passive volume for the same abdominal motion, was more marked in newborns, reflecting their higher chest wall compliance. The work per minute, computed from the pressure and volume changes, was larger in piglets. After vagotomy the external work per minute was not different; however, the larger tidal volumes were accompanied by a larger chest distortion. This may indicate that vagal control of the breathing pattern, by limiting the depth of inspiration and hence the amount of chest distortion, has implications on the energetics of breathing
The action of glibenclamide on diaphragmatic strength and endurance during endotoxaemic shock in pigs
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