American journal of physiology. Regulatory, integrative and comparative physiology
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Am. J. Physiol. Regul. Integr. Comp. Physiol. · Nov 2010
Comparative StudyThe water-absorption region of ventral skin of several semiterrestrial and aquatic anuran amphibians identified by aquaporins.
Regions of specialization for water absorption across the skin of Bufonid and Ranid anurans were identified by immunohistochemistry and Western blot analysis, using antibodies raised against arginine vasotocin (AVT)-stimulated aquaporins (AQPs) that are specific to absorbing regions of Hyla japonica. In Bufo marinus, labeling for Hyla urinary bladder-type AQP (AQP-h2), which is also localized in the urinary bladder, occurred in the ventral surface of the hindlimb, pelvic, and pectoral regions. AQP-h2 was not detected in any skin regions of Rana catesbeiana, Rana japonica, or Rana nigromaculata. ⋯ In contrast, 10(-8) M AVT-stimulated water permeability and translocation of AQP-h2 and AQP-h3 into the apical membrane of epithelial cells in regions of the skin of species where they had been localized by immunohistochemistry and Western blot analysis. Finally, water permeability of the hindlimb skin of B. marinus and all the Rana species was stimulated by hydrins 1 and 2 to a similar level as seen for AVT. The present data demonstrate species differences in the occurrence, distribution, and regulation of AQPs in regions of skin specialized for rapid water absorption that can be associated with habitat and also phylogeny.
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Am. J. Physiol. Regul. Integr. Comp. Physiol. · Nov 2010
Randomized Controlled Trial Multicenter StudyVentilatory restraint of sympathetic activity during chemoreflex stress.
The within-breath modulation of muscle sympathetic nerve activity (MSNA) is well established, with greater activity occurring during expiration and less during inspiration. Whether ventilation per se affects the longer-term (i.e., minute-to-minute) regulation of MSNA has not been determined. We sought to define the specific role of ventilation in regulating sympathetic activation during chemoreflex activation, where both ventilation and MSNA are increased. ⋯ The augmented sympathetic response during apneas was associated with a larger pressor response and total peripheral resistance compared with rebreathing. These data demonstrate that ventilation per se restrains sympathetic activation during chemoreflex activation. Further, the augmented sympathetic response during apneas was associated with greater cardiovascular stress and may be relevant to the cardiovascular pathology associated with sleep-disordered breathing.
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Am. J. Physiol. Regul. Integr. Comp. Physiol. · Nov 2010
Comparative StudyAdaptive thermogenesis and thermal conductance in wild-type and UCP1-KO mice.
We compared maximal cold-induced heat production (HPmax) and cold limits between warm (WA; 27°C), moderate cold (MCA; 18°C), or cold acclimated (CA; 5°C) wild-type and uncoupling-protein 1 knockout (UCP1-KO) mice. In wild-type mice, HPmax was successively increased after MCA and CA, and the cold limit was lowered to -8.3°C and -18.0°C, respectively. UCP1-KO mice also increased HPmax in response to MCA and CA, although to a lesser extent. ⋯ Neither respiration nor basal proton conductance of skeletal muscle mitochondria were different between genotypes. In subcutaneous white adipose tissue of UCP1-KO mice, cold exposure increased cytochrome-c oxidase activity and expression of the cell death-inducing DFFA-like effector A by 3.6-fold and 15-fold, respectively, indicating the recruitment of mitochondria-rich brown adipocyte-like cells. Absence of functional BAT leads to remodeling of white adipose tissue, which may significantly contribute to adaptive thermogenesis during cold acclimation.
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Am. J. Physiol. Regul. Integr. Comp. Physiol. · Nov 2010
Complement factor 3 deficiency attenuates hemorrhagic shock-related hepatic injury and systemic inflammatory response syndrome.
Although complement activation is known to occur in the setting of severe hemorrhagic shock and tissue trauma (HS/T), the extent to which complement drives the initial inflammatory response and end-organ damage is uncertain. In this study, complement factor 3-deficient (C3(-/-)) mice and wild-type control mice were subjected to 1.5-h hemorrhagic shock, bilateral femur fracture, and soft tissue injury, followed by 4.5-h resuscitation (HS/T). C57BL/6 mice were also given 15 U of cobra venom factor (CVF) or phosphate-buffered saline injected intraperitoneally, followed by HS/T 24 h later. ⋯ C3(-/-) mice subjected to HS/T had higher levels of heme oxygenase-1, which has been associated with tissue protection in HS models. Our data indicate that complement activation contributes to inflammatory pathways and liver damage in HS/T. This suggests that targeting complement activation in the setting of severe injury could be useful.