American journal of physiology. Regulatory, integrative and comparative physiology
-
Am. J. Physiol. Regul. Integr. Comp. Physiol. · Aug 2000
Fictive locomotion and scratching inhibit dorsal horn neurons receiving thin fiber afferent input.
In decerebrate paralyzed cats, we examined the effects of two central motor commands (fictive locomotion and scratching) on the discharge of dorsal horn neurons receiving input from group III and IV tibial nerve afferents. We recorded the impulse activity of 74 dorsal horn neurons, each of which received group III input from the tibial nerve. Electrical stimulation of the mesencephalic locomotor region (MLR), which evoked fictive static contraction or fictive locomotion, inhibited the discharge of 44 of the 64 dorsal horn neurons tested. ⋯ Stimulation of the MLR or the elicitation of fictive scratching had no effect on the activity of 22 dorsal horn neurons receiving input from group III and IV tibial nerve afferents. The mean depth from the dorsal surface of the cord was 1.17 +/- 0.07 mm, a value that was significantly (P < 0.05) less than that for the neurons whose discharge was inhibited by either MLR stimulation or fictive scratching. We conclude that centrally evoked motor commands can inhibit the discharge of dorsal horn neurons receiving thin fiber input from the periphery.
-
Am. J. Physiol. Regul. Integr. Comp. Physiol. · May 2000
Role of endotoxin in the expression of endothelial selectins after cecal ligation and perforation.
The objectives of this study were to determine 1) the changes in endothelial cell adhesion molecule expression that occur in a clinically relevant model of sepsis and 2) the dependence of these changes on endotoxin [lipopolysaccharide (LPS)]. The dual radiolabeled monoclonal antibody technique was used to quantify the expression of E- and P-selectin in LPS-sensitive (C3HeB/FeJ) and LPS-insensitive (C3H/HeJ) mice that were subjected to acute peritonitis by cecal ligation and perforation (CLP). ⋯ An accumulation of granulocytes, assessed using tissue myeloperoxidase activity, was noted in the lung and intestine of LPS-sensitive but not LPS-insensitive mice exposed to CLP. These results indicate that the CLP model of sepsis is associated with an upregulation of endothelial selectins in the gut vasculature and that enteric LPS does not contribute to this endothelial cell activation response.
-
Am. J. Physiol. Regul. Integr. Comp. Physiol. · Apr 2000
Alterations in spinal cord Fos protein expression induced by bladder stimulation following cystitis.
These studies examined Fos protein expression in spinal cord neurons synaptically activated by stimulation of bladder afferent pathways after cyclophosphamide (CYP)-induced bladder inflammation. In urethan-anesthetized Wistar rats with cystitis, intravesical saline distension significantly (P
-
Am. J. Physiol. Regul. Integr. Comp. Physiol. · Feb 2000
Effects of a unique conjugate of alpha-lipoic acid and gamma-linolenic acid on insulin action in obese Zucker rats.
The purpose of this study was to assess the individual and interactive effects of the antioxidant alpha-lipoic acid (LPA) and the n-6 essential fatty acid gamma-linolenic acid (GLA) on insulin action in insulin-resistant obese Zucker rats. LPA, GLA, and a unique conjugate consisting of equimolar parts of LPA and GLA (LPA-GLA) were administered for 14 days at 10, 30, or 50 mg. kg body wt(-1). day(-1). Whereas LPA was without effect at 10 mg/kg, at 30 and 50 mg/kg it elicited 23% reductions (P < 0.05) in the glucose-insulin index (the product of glucose and insulin areas under the curve during an oral glucose tolerance test and an index of peripheral insulin action) that were associated with significant increases in insulin-mediated (2 mU/ml) glucose transport activity in isolated epitrochlearis (63-65%) and soleus (33-41%) muscles. ⋯ At 50 mg/kg, the metabolic improvements due to LPA-GLA were substantially reduced. In summary, these results indicate that the conjugate of the antioxidant LPA and the n-6 essential fatty acid GLA elicits significant dose-dependent improvements in whole body and skeletal muscle insulin action on glucose disposal in insulin-resistant obese Zucker rats. Moreover, these actions of LPA-GLA are due to the additive effects of its individual components.
-
Am. J. Physiol. Regul. Integr. Comp. Physiol. · Feb 2000
Accelerated contractile function and improved fatigue resistance of calf muscles in newborn piglets with IUGR.
Asymmetrical intrauterine growth restriction is denoted by disproportional reduction of muscle mass compared with body weight reduction. However, effects on contractile function or tissue development of skeletal muscles were not studied until now. Therefore, isometric force output of serial-stimulated hindlimb plantar flexors was measured in thiopental-anesthetized normal weight (NW) and intrauterine growth-restricted (IUGR) 1-day-old piglets under conditions of normal, reduced (aortic cross clamping), and reestablished (clamp release) blood supply (measured by colored microspheres technique). ⋯ Functional restoration of contractile performance after hindlimb recirculation was nearly complete in IUGR piglets (98 +/- 1%), whereas in NW piglets a deficit of 9 +/- 3% was found (P < 0. 01). Muscle fiber type estimation revealed an increased proportion of type I fibers in flexor digitalis superficialis and gastrocnemius medialis in IUGR piglets (P < 0.05). These data clearly indicate that contractile function is accelerated in newborn IUGR piglets.