1,721,051 research outputs found
Endothelin-1 and breathing pattern in pig
No full textThe respiratory and vascular effects of Endothelin-1 (ET-1) were evaluated in six anesthetized and spontaneously breathing pigs. ET-1 was administered intrajugularly as a bolus of 100 pmol/Kg. Then the vascular effects of the peptide, administered at the same dose, were evaluated in the same pigs during mechanical ventilation. Our results show that during mechanical ventilation ET-1 has a biphasic effect on pulmonary and systemic arterial pressure, while in spontaneously breathing pigs it affects only pulmonary arterial pressure. Our results also show that ET-1 changes the breathing pattern, lengthening the inspiration and expiration times. During pulmonary hypertension, the lengthening might be due to a vagal reflex, while during pulmonary hypotension it might be due to direct involvement of ET-1 in the control of the breathing pattern
EMG del diaframma costale e crurale nel maiale neonato
No full textThe EMG of costal and crural diaphragm has been evaluated in 6 anaesthetized (Thiopentale mg 15/kg i.v.) and tracheostomized newborn pigs, 3-5 days old. The EMG has been evaluated in control condition, during resistive load and during PGF2alpha bronchoconstriction (mg 0.150-0.200/kg i.v.). Results evidenced that resistive load and bronchoconstriction cause an increase in Pdi and in EMG of costal and crural diaphragm. For a similar change in Pdi the costal and crural diaphragm activity is greater during PGF2alpha bronchoconstriction. The results evidence a central PGF2alpha activity on respiratory centers
Differente coinvolgimento dell’ossido d’azoto e della prostaciclina nella regolazione del tono vascolare sistemico e polmonare
No full textIn 14 anaesthetized and mechanically ventilated Large White pigs we analysed the involvement of nitric oxide (NO) and prostanoids in the regulation of systemic and pulmonary vascular tone. Endogenous release of NO was blocked by NG-nitro-L-arginine methyl ester (L-NAME 5 mg/kg i.v.), while prostanoids biosynthesis was blocked by indomethacin (3 mg/kg i.v.). The subsequent parameters have been evaluated: systemic (MAP) and pulmonary arterial pressure (MPAP), cardiac output (CO), heart rate (HR) and systemic (SVR) and pulmonary vascular resistances (PVR). Blocking NO increased MAP, MPAP and vascular resistances. These effects evidence that in pig the vascular tone is modulated by a continuous release of NO by endothelial cells. The block of prostanoids biosynthesis did not affect the vasoconstrictor effect of L-NAME on the pulmonary vascular bed, but strengthened its hypertensive effect on systemic one. Consequently these data show that systemic and pulmonary vascular tones are differently regulated
In pigs, inhaled nitric oxide (NO) counterbalances PAF-induced pulmonary hypertension
No full textIn 6 anesthetized mechanically ventilated pigs we have studied the effects of inhalation of 80 ppm of nitric oxide (NO) before and after platelet-activating factor (PAF) administration (50 ng/kg iv). Our results show that NO inhalation causes a decrease in pulmonary arterial pressure and in heart rate without affecting other circulatory parameters. PAF administration causes a pulmonary hypertension and a prompt and brief decrease in systemic pressure. Inhalation of NO reduces the pulmonary hypertension, without completely reversing PAF-dependent vasoconstriction. PAF administration to pigs pretreated with indomethacin produces a lesser increase in pulmonary vascular pressure. In this case, NO inhalation can restore to baseline values. Pretreatment of 3 of the 6 pigs with NG-nitro-l-arginine-methyl-ester did not prevent the prompt and brief PAF-induced systemic hypotension. In conclusion, our results show that NO reduces basal pulmonary vascular tone, acts as a pulmonary vasodilator on PAF-preconstricted vessels and is not involved in the brief systemic hypotension consequent to PAF administration
Interazioni tra platelet activating factor (PAF), ossido d’azoto (NO) ed endotelina-1 (ET-1) sul circolo polmonare e sistemico e sulla meccanica respiratoria nel suino
No full textIn 9 anaesthetized and mechanically ventilated Large White pigs, we analyzed the effects of Platelet Activating Factor (PAF 50 ng/kg i.v.) on circulatory and mechanical respiratory parameters, before and after administration of NG-nitro-L-arginine methyl ester (L-NAME, 5 mg/kg i.v.), a blocker of nitric oxide synthase and Bosentan (15 mg/kg i.v.), a blocker of endothelin-1 (ET-1) receptors. Our results showed that PAF increased pulmonary (PAPM) and decreased systemic (PAM) arterial pressures; these effects were reduced in animals pretreated with L-NAME and Bosentan. The pretreatment with these two antagonists avoided the increse in resistances (Rrs) and the decrease in passive compliance (Crs) of the respiratory system due to PAF administration
Ruolo dell’endotelina-1 (ET-1) e dei canali K+ATP sulla circolazione polmonare e sistemica nel suino in condizioni di ipossia
No full textIn six spontaneously breathing pigs, we studied the role of arachidonic acid metabolites, endothelin-1 (ET-1) and K+ATP channels on systemic and pulmonary vascular beds, during hypoxia (O2 10% in air). The effects of hypoxia were studied in control conditions, after block of prostanoids by indomethacin, after block of ET-1 receptors by Bosentan and after opening of K+ATP channels by Cromakalim. Bosentan and Cromakalim were administered after pretreatment with indomethacin. Results show that the pulmonary hypertension and the modest increase in systemic arterial pressure hypoxia-dependent are caused by the release of ET-1 and can be counterbalanced by the opening of K+ATP channels. Hypoxia does not modify cardiac output and heart rate, therefore the observed changes in pulmonary and systemic vascular resistances seem essentialy due to a change in pulmonary and systemic pressures
Inhaled nitric oxide reverses PAF-dependent bronchoconstriction in the pig
No full textIn six anesthetized, paralyzed, mechanically ventilated pigs we evaluated the respiratory effects of inhaled nitric oxide (NO) (80 ppm in O2) under control conditions and after platelet-activating factor (PAF) administration (50 ng/kg, i.v.). PAF was also administered to the same pigs after pretreatment with indomethacin (3 mg/kg, i.v.). The mechanical properties of the respiratory system were evaluated by the rapid airway occlusion technique. With this technique the overall respiratory resistances, the airway resistances, and the additional resistances of respiratory system and lung can be evaluated. The results show that NO inhaled by the pig at 80 ppm for 6 min under control conditions reduced static and dynamic elastances of the respiratory system and lung and pulmonary arterial pressure, without modifying bronchomotor tone. Therefore, NO reduced the PAF-dependent changes in resistances and in static and dynamic elastances of the respiratory system and lung. The modest change in elastances caused by PAF in pigs pretreated with indomethacin was reduced by NO inhalation, which also has a mild bronchodilatory effect. The changes in elastances appear to be correlated with the pulmonary vasodilator activity of inhaled NO
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