In this Issue
September 2016; volume 121, issue 3
Editorial
Articles
- Differential effects of respiratory and electrical stimulation-induced dilator muscle contraction on mechanical properties of the pharynx in the pig
Respiratory stimulation and electrical stimulation of the hypoglossus nerve differ in the mechanism by which they stabilize the pharynx in the isolated upper airway of the pig: respiratory stimulation reduces pharyngeal compliance, i.e., stiffens the area of collapse, whereas electrical stimulation lowers extrapharyngeal pressure, as calculated from the area-pressure curve. Tongue muscles, but not the neck muscles and thoracic forces, contributed to the respiratory stimulation-induced stiffening of the pharynx in this study.
- Evaluating the control: minipump implantation and breathing behavior in the neonatal rat
Accumulating evidence indicates that gestational and/or neonatal stress perturbs central nervous system (CNS) development and that fetal exposure to anesthetic agents or narcotics disrupts critical processes of axonal growth and synapse elimination. Here we focus on processes related to minipump implantation surgery and the potential impact of implant surgery on early postnatal respiratory control and function.
- Exercise physiological responses to drug treatments in chronic thromboembolic pulmonary hypertension
This is the first study using gas exchange during exercise to assess the response to pulmonary arterial hypertension drug therapy in patients with chronic thromboembolic pulmonary hypertension. We also for the first time compare patients with operable and inoperable chronic thromboembolic pulmonary hypertension.
- Prolonged adenosine triphosphate infusion and exercise hyperemia in humans
The novel and noteworthy findings are 1) in humans, the vasodilator response to infusion of exogenous ATP does not wane and 2) the magnitude of change in hyperemic responses to exercise during the ATP infusion is unaffected. The ability of ATP to evoke prolonged vasodilation shows it meets a key criterion of any putative dilator substance. The latter observation suggests a disconnect between the usual matching of blood flow and oxygen delivery during contractions.
- Maximal oxygen uptake is proportional to muscle fiber oxidative capacity, from chronic heart failure patients to professional cyclists
Maximal oxygen uptake during whole body exercise is presumably constrained by oxygen delivery to mitochondria rather than by mitochondria's ability to consume oxygen. However, mitochondrial oxidative overcapacity remains unclear due to complicated isolation and permeabilization procedures. In the present study, human maximal oxygen uptake attained during cycling exercise is related and ∼90% of mitochondrial oxidative capacity predicted from skeletal muscle succinate dehydrogenase activity. This mitochondrial oxidative overcapacity is substantially lower than previously reported from isolation and permeabilization procedures.
- Morphological and molecular aspects of immobilization-induced muscle atrophy in rats at different stages of postnatal development: the role of autophagy
Immobilization induces muscle maladaptations at different stages of postnatal development, but the cellular mechanisms involved in such effects are unclear. Our data show that the alterations in muscle proteostasis during immobilization occur in age-independent and -dependent manners and muscle disorders are aggravated by autophagy blockade with colchicine, inducing a myopathic profile. This understanding may help us optimize treatment outcomes in immobilized adults and infants and encourages the testing of different autophagy inhibitors in muscle atrophy.
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