Gender differences in muscle inflammation after eccentric exercise.

Unaccustomed exercise is followed by delayed-onset muscle soreness and morphological changes in skeletal muscle. Animal studies have demonstrated that women have an attenuated response to muscle damage. We studied the effect of eccentric exercise in untrained male (n = 8) and female (n = 8) subjects using a unilateral exercise design [exercise (Ex) and control (Con) legs]. Plasma granulocyte counts [before (Pre) and 48 h after exercise (+48h)] and creatine kinase activity [Pre, 24 h after exercise (+24h), +48h, and 6 days after exercise (+6d)] were determined before (Pre) and after (+24h, +48h, +6d) exercise, with biopsies taken from the vastus lateralis of each leg at +48h for determination of muscle damage and/or inflammation. Plasma granulocyte counts increased for men and decreased for women at +48h (P < 0.05), and creatine kinase activity increased for both genders at +48h and +6d (P < 0.01). There were significantly greater areas of both focal (P < 0.001) and extensive (P < 0.01) damage in the Ex vs. Con leg for both genders, which was assessed by using toluidine blue staining. The number of leukocyte common antigen-positive cells/mm(2) tissue increased with exercise (P < 0.05), and men tended to show more in their Ex vs. Con leg compared with women (P = 0.052). Men had a greater total (Ex and Con legs) number of bcl-2-positive cells/mm(2) tissue vs. women (P < 0.05). Atrophic fibers with homogeneous bcl-2-positive staining were seen only in men (n = 3). We conclude that muscle damage is similar between genders, yet the inflammatory response is attenuated in women vs. men. Finally, exercise may stimulate the expression of proteins involved in apoptosis in skeletal muscle.

The effects of exercise intensity on post exercise hypotension.

Ten normotensive, recreationally active participants aged 35.0 +/- 16.3 years, volunteered to participate in the study. Average baseline blood pressure (BP) was 132/75 mm Hg for systolic (SBP) and diastolic (DBP) pressure respectively. On two separate days, participants underwent testing in a randomised, repeated measures fashion such that they performed 30-min bouts of cycle ergometry at a power output which elicited 50 or 75% of VO2 Peak. Blood pressure was monitored continuously throughout the session by the Finapres method with 2-min windows recorded at rest, 5, 10, 15, 30, 45 and 60 min post exercise. SBP was similar between the two trials and became hypotensive at 5 through 15 min post exercise. The largest decrement (8 mm Hg) in SBP occurred 5 min post exercise. DBP was also unaffected by the intensity of exercise and was lower than before exercise at 5 and 15 through 45 min post exercise. Similarly, mean arterial pressure (MAP) showed significant decrements at 5 and 15 through 45 min post exercise irrespective of exercise intensity. Heart rate was greater during the 75% intensity than during the 50% intensity trial. Pre-exercise values were re-established by 45 min post exercise. VO2 remained significantly elevated above pre-exercise values in both trials until 15 min post exercise. Haematocrit increased significantly during both exercise bouts but returned to pre-exercise values by 10 min post exercise. This study indicates that cycle ergometry at 50 and 75% of VO2 Peak elicit similar reductions in post exercise BP. Therefore bouts of mild to moderate intensity exercise may be beneficial in the control of hypertension.

The effects of exercising muscle mass on post exercise hypotension.

Nine recreationally active, borderline hypertensive subjects completed 30 min of arm ergometry (ARM) at 65% VO2 peak and 30 min of leg ergometry (LEG) at 70% VO2 Peak (randomised order). Blood pressure was monitored before and for 1 h after exercise using the Finapres method. Systolic, diastolic and mean blood pressures were significantly reduced for the entire 1 h post exercise. This reduction was independent of exercise modality, but there was an indication for the duration of the effect to be prolonged following the leg exercise. We conclude that the mass of the working muscle does not directly effect the magnitude of post-exercise hypotension (PEH) but may influence the duration of the response. These results suggest that a central mechanism or decreased vascular responsiveness is responsible for PEH.

The effects of exercise duration on post-exercise hypotension.

STUDY 1: Thirteen normotensive participants with average baseline blood pressure of 126/71 mm Hg participated in the study. Participants performed bouts of cycle ergometry for 15, 30 and 45 min at 70% VO2 Peak. Blood pressure was monitored by the Finapres method with 2 min windows recorded at rest, 5, 10, 15, 30, 45 and 60 min post-exercise. Following exercise, systolic blood pressure (SBP) was similar between the three trials and was reduced from pre-exercise values at 5 through 60 min of measurement. Diastolic blood pressure (DBP) was also unaffected by the duration of exercise and was lower than before exercise at 30 through 45 min post-exercise. STUDY 2: Eight borderline hypertensive participants with average baseline blood pressure of 133/79 mm Hg participated in the study. Subjects performed bouts of cycle ergometry for 10 and 30 min at 70% VO2 Peak. Following exercise, blood pressure was monitored as in study 1. SBP was similar between both trials and was reduced from baseline at 5 through 60 min post-exercise. The largest decrement of SBP was 14 mm Hg and occurred 15 min post-exercise. DBP was also unaffected by the duration of exercise and was lower than pre-exercise levels at 5 min and again at 15 through 45 min post-exercise. Mean arterial pressure (MAP) also showed significant decrements throughout the entire 1 h post-exercise period by a maximum of 9 mm Hg at 15 min post-exercise, irrespective of exercise duration. We conclude that moderately intense exercise may be as brief as 10 min in duration in order to elicit a decrease in resting blood pressure and may have potential benefits as a non-pharmacological aid to hypertension.

Post exercise hypotension is sustained during subsequent bouts of mild exercise and simulated activities of daily living.

Our purpose was to examine whether the transient suppression of blood pressure that occurs during the hours following acute exercise (termed post exercise hypotension) persists throughout an active period of subsequent mild exercise and simulated activities of daily living (ADL) using direct measurements of arterial pressure. Eight recreationally active participants, with low borderline systolic hypertension completed 30 min of cycle ergometry at 70% VO(2Peak) and 30 min of quiet seated rest on separate days (randomised order). Following exercise and rest, subjects completed a 70-min protocol of mild exercise and simulated ADL. Blood pressure was monitored throughout by catheterisation of the radial artery. Exercise resulted in lower systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) throughout the post exercise ADL period compared to control measurements taken without prior exercise. The maximal difference in SBP, DBP and MAP between trials was 26, 7 and 13 mm Hg respectively. Average differences in SBP, DBP and MAP between trials were 16, 5 and 8 mm Hg respectively. This relative hypotension occurred in spite of higher heart rates during the ADL measurement period following the prior exercise. Furthermore, many of the blood pressure measurements during the post exercise period were significantly lower than the pre-exercise values during the same trial. We conclude that post exercise hypotension persists during mild exercise and simulated ADL. Although the duration of this relative hypotension needs to be determined, acute exercise may serve as a non-pharmacological aid in the treatment of hypertension.

Post exercise hypotension is not mediated by the serotonergic system in borderline hypertensive individuals.

Recent evidence from our laboratory and others have suggested that the mechanism for a decrease in resting blood pressure after an acute bout of exercise is a centrally mediated decrease in total peripheral resistance. This study examined the effect of the central serotonergic system on post exercise hypotension (PEH) in 11 borderline hypertensive individuals (nine male, two female) aged 24.5 +/- 5.1 years. Each subject completed two, 30-min cycling bouts at 70% of VO2peak while under placebo or a selective serotonin re-uptake inhibitor (SSRI) treatment. Blood pressure was recorded directly from the radial artery, and treatments were randomised, double blinded and separated by at least 14 days. Baseline blood pressure was 145/72 mm Hg for systolic (SBP) and diastolic (DBP) respectively. Peripheral measures of serotonin (5-HT) were lower under SSRI treatment, whereas the major 5-HT metabolite, 5-hydroxyindoleacetic acid, was not significantly changed, indicating elevated central 5-HT levels. There was no difference in any of the haemodynamic variables between trials. Despite an increased heart rate for the initial 75 min post exercise, SBP was decreased as much as 23 mm Hg during the initial 60 min post exercise, after which it had returned to normal. DBP was unchanged after exercise. Circulating adrenaline (0.60 +/- 0.14 ng/mL to 1.3 +/- 1.6 ng/ml) and noradrenaline (0.27 +/- 0.31 ng/ml to 4.5 +/- 2.1 ng/ml) were significantly elevated during exercise. Both returned to pre-exercise levels within 15 min post exercise. Unexpectedly, oxygen uptake was slightly (5%), but significantly increased over the entire duration of the SSRI trial. We conclude that the central serotonergic system is not responsible for PEH in our borderline hypertensive population.

An arc control and protection system for the JET lower hybrid antenna based on an imaging system.

Arcs are the potentially most dangerous events related to Lower Hybrid (LH) antenna operation. If left uncontrolled they can produce damage and cause plasma disruption by impurity influx. To address this issue an arc real time control and protection imaging system for the Joint European Torus (JET) LH antenna has been implemented. The LH system is one of the additional heating systems at JET. It comprises 24 microwave generators (klystrons, operating at 3.7 GHz) providing up to 5 MW of heating and current drive to the JET plasma. This is done through an antenna composed of an array of waveguides facing the plasma. The protection system presented here is based primarily on an imaging arc detection and real time control system. It has adapted the ITER like wall hotspot protection system using an identical CCD camera and real time image processing unit. A filter has been installed to avoid saturation and spurious system triggers caused by ionization light. The antenna is divided in 24 Regions Of Interest (ROIs) each one corresponding to one klystron. If an arc precursor is detected in a ROI, power is reduced locally with subsequent potential damage and plasma disruption avoided. The power is subsequently reinstated if, during a defined interval of time, arcing is confirmed not to be present by image analysis. This system was successfully commissioned during the restart phase and beginning of the 2013 scientific campaign. Since its installation and commissioning, arcs and related phenomena have been prevented. In this contribution we briefly describe the camera, image processing, and real time control systems. Most importantly, we demonstrate that an LH antenna arc protection system based on CCD camera imaging systems works. Examples of both controlled and uncontrolled LH arc events and their consequences are shown.

A new visible spectroscopy diagnostic for the JET ITER-like wall main chamber.

In preparation for ITER, JET has been upgraded with a new ITER-like wall (ILW), whereby the main plasma facing components, previously of carbon, have been replaced by mainly Be in the main chamber and W in the divertor. As part of the many diagnostic enhancements, a new, survey, visible spectroscopy diagnostic has been installed for the characterization of the ILW. An array of eight lines-of-sight (LOS) view radially one of the two JET neutral beam shine through areas (W coated carbon fibre composite tiles) at the inner wall. In addition, one vertical LOS views the solid W tile at the outer divertor. The light emitted from the plasma is coupled to a series of compact overview spectrometers, with overall wavelength range of 380-960 nm and to one high resolution Echelle overview spectrometer covering the wavelength range 365-720 nm. The new survey diagnostic has been absolutely calibrated in situ by means of a radiometric light source placed inside the JET vessel in front of the whole optical path and operated by remote handling. The diagnostic is operated in every JET discharge, routinely monitoring photon fluxes from intrinsic and extrinsic impurities (e.g., Be, C, W, N, and Ne), molecules (e.g., BeD, D(2), ND) and main chamber and divertor recycling (typically Dα, Dß, and Dγ). The paper presents a technical description of the diagnostic and first measurements during JET discharges.

Enhancements to the JET poloidally scanning vacuum ultraviolet∕visible spectrometers.

Enhancements to the JET poloidally scanning spectrometers are presented, which will aid the exploitation of the recently installed ITER-like wall in JET. They include the installation of visible filter∕photomultiplier tube assemblies and spectrometers and the replacement of large rotating mirrors in the JET vacuum with small oscillating mirrors outside. The upgrade has resulted in a more robust and reliable diagnostic than before, which is described. Drifts in the mirror angle reconstructed from quadrature encoder signals are found, a reference signal being required. The use of the small scanning mirrors necessitated the inclusion of focusing mirrors to maintain throughput into the vacuum ultraviolet spectrometers. The mirror design has taken account of the extreme sensitivity of the focusing to the grazing angle of incidence, an aspect of importance in the design of grazing incidence focusing components on future machines, such as ITER. The visible system has been absolutely calibrated using an in-vessel light source.

Multiband reflectometry system for density profile measurement with high temporal resolution on JET tokamak.

A new system has been installed on the JET tokamak consisting of six independent fast-sweeping reflectometers covering four bands between 44 and 150 GHz and using orthogonal polarizations. It has been designed to measure density profiles from the plasma edge to the center, launching microwaves through 40 m of oversized corrugated waveguides. It has routinely produced density profiles with a maximum repetition rate of one profile every 15 µs and up to 100,000 profiles per pulse.

Heart fatty acid binding protein is a novel regulator of cardiac myocyte hypertrophy.

Heart fatty acid binding protein (H-FABP) is a 15kDa protein that mediates the passage of fatty acids from the plasma membrane to sites of lipid synthesis. We report here, for the first time, that H-FABP is a potent inducer of cardiac myocyte hypertrophy, stimulating an increase in cell surface area, protein synthesis and c-jun expression. A high affinity receptor for H-FABP has also been identified. Taken together, these data suggest that H-FABP may participate in the regulation of cardiac myocyte growth and differentiation.