Adductor pollicis muscle function of a 21-year-old man with genetically confirmed Brody's disease (sarcoplasmic reticulum [SR] -Ca2+ATPase deficiency) was investigated to study the possible effects of reduced SR-Ca2+ATPase activity on muscle relaxation and force production. Following maximal electrical activation of the ulnar nerve, tetanic muscle half-relaxation time was greater in the patient...

We measured the characteristics of the decline in tension during isometric relaxation of canine papillary muscle. In the intact heart, relaxation begins with the isovolumic phase, but in experiments on papillary muscle previously reported the isotonic phase preceded the isometric phase during the course of relaxation. In our experiments, however, the isotonic bar was locked at the instant the m...

BACKGROUND Human gastric fundus relaxation is mediated by intrinsic inhibitory pathway. We investigated the roles of nitrergic and purinergic pathways, two known inhibitory factors in gastric motility, on spontaneous and nerve-evoked contractions in human gastric fundus muscles. METHODS Gastric fundus muscle strips (12 circular and 13 longitudinal) were obtained from patients without previous...

The possible functional coupling between beta1-adrenoceptor and MaxiK channels which results in smooth muscle relaxation was examined in the guinea-pig esophageal muscularis mucosae. Isoprenaline-elicited relaxation of esophageal smooth muscle was confirmed to be mediated through beta1-adrenoceptors as the response was competitively antagonized by a beta1-selective antagonist atenolol with a pA...

Neuro-effector transmission and mechanical responses in smooth muscles of the dog iris were studied, using tension recording and microelectrode methods. Electrical stimulations evoked an initial phasic contraction followed by relaxation in both the iris sphincter and dilator muscles. Atropine selectively suppressed phasic contraction of the sphincter and relaxation of the dilator muscle, while ...

Contraction time, time to peak rate of tension development, half-relaxation time and maximum twitch tension of partially denervated flexor carpi ulnaris muscle were measured in children with brachial plexus birth palsy. The extent of weakness of the affected muscle was assessed by expressing its maximum twitch tension as a percentage of the tension of the contralateral normal muscle. Contractio...

Relaxation rate is an important determinant of axial muscle power production during the oscillatory contractions of undulatory locomotion. Recently, significant differences have been reported in the relaxation rates of rostral versus caudal white muscle fibers of the Atlantic cod Gadus morhua L. The present study investigates the biochemical correlates of this rostral-caudal physiological varia...

Smooth muscle membrane potential and tension in rat isolated small mesenteric arteries (inner diameter 100-200 microm) were measured simultaneously to investigate whether the intensity of smooth muscle stimulation and the endothelium influence responses to exogenous K+. Variable smooth muscle depolarization and contraction were stimulated by titration with 0.1-10 microM phenylephrine. Raising e...

Brain activity associated with voluntary muscle relaxation was examined by applying event-related functional magnetic resonance imaging (fMRI) technique, which enables us to observe change of fMRI signals associated with a single motor trial. The subject voluntarily relaxed or contracted the right upper limb muscles. Each motor mode had two conditions; one required joint movement, and the other...

Upper airway (UA) muscle activity is stimulated by changes in UA transmural pressure and by asphyxia. These responses are reduced by muscle relaxation. We hypothesized that this is due to a change in afferent feedback in the ansa hypoglossi and/or superior laryngeal nerve (SLN). We examined 1) the glossopharyngeal motor responses to UA transmural pressure and asphyxia and 2) how these responses...