This study aimed to determine the role of protein kinase C (PKC) in signal transduction mechanisms underlying ventilatory regulation in the nucleus tractus solitarii (NTS). Microinjection of phorbol 12-myristate 13-acetate into the commissural NTS of nine chronically instrumented, unrestrained rats elicited significant cardiorespiratory enhancements that lasted for at least 4 h, whereas administration of vehicle (n = 15) or the inactive phorbol ester 4alpha-phorbol 12,13-didecanoate (n = 7) did not elicit minute ventilation (VE) changes. Peak hypoxic VE responses (10% O2-balance N2) were measured in 19 additional animals after NTS microinjection of bisindolylmaleimide (BIM) I, a selective PKC inhibitor (n = 12), BIM V (inactive analog; n = 7), or vehicle (Con; n = 19). In Con, VE increased from 139 +/- 9 to 285 +/- 26 ml/min in room air and hypoxia, respectively, and similar responses occurred after BIM V. BIM I did not affect room air VE but markedly attenuated hypoxia-induced VE increases (128 +/- 12 to 167 +/- 18 ml/min; P < 0. 02 vs. Con and BIM V). When BIM I was microinjected into the cerebellum (n = 4), cortex (n = 4), or spinal cord (n = 4), VE responses were similar to Con. Western blots of subcellular fractions of dorsocaudal brain stem lysates revealed translocation of PKCalpha, beta, gamma, delta, epsilon, and iota isoenzymes during acute hypoxia, and enhanced overall PKC activity was confirmed in the particulate fraction of dorsocaudal brain stem lysates harvested after acute hypoxia. These studies suggest that, in the adult rat, PKC activation in the NTS mediates essential components of the acute hypoxic ventilatory response.
Poultry-emitted air pollutants, including particulate matter (PM) and ammonia, have raised concerns due to potential negative effects on human health and the environment. However, developing and optimizing remediation technologies requires a better understanding of air pollutant concentrations, the emission plumes, and the relationships between the pollutants. Therefore, we conducted ten field experiments to characterize PM (total suspended particulate [TSP], particulate matter less than 10 μm in aerodynamic diameter [PM], and particulate matter less than 2.5 μm in aerodynamic diameter [PM]) and ammonia emission-concentration profiles from a typical commercial poultry house. The emission factors of the poultry house, which were calculated using the concentrations and fan speed, were 0.66 (0.29-0.99) g NH-N birdd for ammonia, 52 (44-168) g dAU (AU = animal unit = 500 kg) for TSP, 3.48 (1.16-9.03) g dAU for PM, and 0.07 (0.00-0.36) g dAU for PM. PM and ammonia emission concentrations decreased as distance from the fan increased. Although emission concentrations were similar in the daytime and nighttime, diurnal and nocturnal plume shapes were different due to the increased stability of the atmosphere at night. Particle size distribution analysis revealed that, at a given height, the percentage of PM and PM was consistent throughout the plume, indicating that the larger particles were not settling out of the airstream faster than the smaller particles. Overall, the direction of the measured air pollutant emission plumes was dominated by the tunnel fan ventilation airflow rate and direction instead of the ambient wind speed and direction. This is important because currently-available air dispersion models use ambient or modeled wind speed and direction as input parameters. Thus, results will be useful in evaluating dispersion models for ground-level, horizontally-released, point sources and in developing effective pollutant remediation strategies for emissions.
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