scholarly journals Force‐calcium relationships in intact skeletal muscle: effects of temperature

2007 ◽  
Vol 21 (6) ◽  
Author(s):  
Thomas L Clanton
Keyword(s):  
Skeletal Muscle ◽  
Effects Of Temperature

Effects of temperature on muscle pHi and phosphate metabolites in newts and lungless salamanders

1993 ◽  
Vol 265 (5) ◽  
pp. R1162-R1167 ◽  
Author(s):  
D. C. Johnson ◽  
C. T. Burt ◽  
W. C. Perng ◽  
B. M. Hitzig
Keyword(s):  
Skeletal Muscle ◽  
Skeletal Muscle Cell ◽  
Resonance Spectroscopy ◽  
Behavioral Regulation ◽  
Acid Base ◽  
Acid Base Status ◽  
Cell Cytosol ◽  
Effects Of Temperature ◽  
Increasing Temperature ◽  
Tail Muscle

The effect of acute alterations in body temperature (BT) on intracellular pH (pHi) and phosphate metabolites was assessed in white skeletal muscle of intact newts and lungless red-backed salamanders using 31P-nuclear magnetic resonance spectroscopy. pHi decreased with increasing BT in the tail muscle of both newts and lungless red-backed salamanders. The change in pH with change in temperature from 10 to 30 degrees C was -0.018 U/degrees C in newts and -0.041 U/degrees C in red backs. The calculated alpha-imidazole for skeletal muscle cytosol did not change (0.56) in newts from 10 to 30 degrees C but fell from 0.69 to 0.43 in red-backed salamanders. Phosphocreatine (PCr)/Pi fell and Pi/beta-ATP rose with increasing temperature in both newts and red backs; however, the change was much greater in red backs. Providing the red backs with O2 at 30 degrees C led to higher pH and alpha-imidazole, comparable to that of newts, along with increased PCr/Pi and lower Pi/beta-ATP. Thus newts maintain white skeletal muscle cell cytosol alpha-imidazole constant with changes in BT, whereas red backs apparently do not. However, at the BT of preference, red backs and newts maintain similar muscle pHi and alpha-imidazole. The method of gas exchange appears to strongly influence the ability of an animal to maintain its acid-base status over a range of temperatures, and our results suggest that behavioral regulation of BT may involve alpha-imidazole regulation as well.

Beta-adrenergic receptors in skeletal muscles of ruminants: Effects of temperature and feed intake

2000 ◽  
Vol 80 (1) ◽  
pp. 79-86 ◽  
Author(s):  
E. D. Ekpe ◽  
J. A. Moibi ◽  
R. J. Christopherson
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Feed Intake ◽  
Adrenergic Receptors ◽  
Experimental Treatment ◽  
Biceps Femoris ◽  
Effect Of Temperature ◽  
Feed Restriction ◽  
Binding Affinities ◽  
Effects Of Temperature

Adrenergic receptors mediate effects of catecholamines on physiological processes including protein and energy metabolism. We determined the effects of temperature and feed intake on beta-1 and beta-2 adrenergic receptors (β1 AR and β2 AR) in skeletal muscle of lambs to assess the potential to modify physiological responses through adrenergic receptors. Twenty-four wether lambs received either restricted (R) or ad libitum (A) levels of feed intake, and were exposed to either cold (C; 0 ± 2 °C) or warm (W; 23 ± 2 °C) temperatures, resulting in four experimental treatment groups (WA, WR, CA and CR). At the end of 4 mo the lambs were slaughtered and biceps femoris, semitendinosus and gastrocnemius muscles were harvested for isolation of plasma membrane. Binding of [3H]dihydroalprenolol to crude plasma membrane was used to determine the β AR densities and binding affinities (Kd). The densities of β1 AR were 28.02 ± 4.17, 40.68 ± 2.26, 28.99 ± 4.68 and 55.56 ± 6.05 fmol mg−1 protein for biceps femoris, 29.35 ± 1.49, 35.34 ± 2.59, 28.36 ± 2.94 and 37.89 ± 3.30 fmol mg−1 protein for gastrocnemius, and 22.66 ± 2.66, 31.21 ± 4.65, 21.84 ± 1.81 and 38.62 ± 3.67 fmol mg−1 protein for semitendinosus, for WA, WR, CA and CR, respectively. The Kd values for all groups ranged from 1.7 to 8.5 nM for β1 AR. Feed restriction increased (P < 0.01) the density of β1 AR in both environments but there was no significant effect of temperature. β1 AR densities and binding affinities were significantly higher in biceps femoris than in gastrocnemius and semitendinosus muscles when feed intake was restricted. The densities of β2 AR ranged from 9.0 to 16.0 fmol mg−1 protein. There was no effect of treatments on the density or receptor binding affinity of β2 AR in muscles. It is concluded that feed restriction causes increased density of β1 AR in sheep and that feed restriction could potentially increase the metabolic responsiveness of skeletal muscle to elevated levels of catecholamines. Key words: Catecholamine receptors, skeletal muscle, temperature, feed

Effects of temperature on slow and fast inactivation of rat skeletal muscle Na+channels

1999 ◽  
Vol 277 (5) ◽  
pp. C937-C947 ◽  
Author(s):  
Robert L. Ruff
Keyword(s):  
Skeletal Muscle ◽  
Potential Temperature ◽  
Resting Potential ◽  
Mammalian Skeletal Muscle ◽  
Slow Inactivation ◽  
Fast Inactivation ◽  
Effects Of Temperature ◽  
Increasing Temperature ◽  
Fast Twitch

Patch-clamp studies of mammalian skeletal muscle Na+ channels are commonly done at subphysiological temperatures, usually room temperature. However, at subphysiological temperatures, most Na+ channels are inactivated at the cell resting potential. This study examined the effects of temperature on fast and slow inactivation of Na+ channels to determine if temperature changed the fraction of Na+ channels that were excitable at resting potential. The loose patch voltage clamp recorded Na+ currents ( I Na) in vitro at 19, 25, 31, and 37°C from the sarcolemma of rat type IIb fast-twitch omohyoid skeletal muscle fibers. Temperature affected the fraction of Na+ channels that were excitable at the resting potential. At 19°C, only 30% of channels were excitable at the resting potential. In contrast, at 37°C, 93% of Na+ channels were excitable at the resting potential. Temperature did not alter the resting potential or the voltage dependencies of activation or fast inactivation. I Na available at the resting potential increased with temperature because the steady-state voltage dependence of slow inactivation shifted in a depolarizing direction with increasing temperature. The membrane potential at which half of the Na+channels were in the slow inactivated state was shifted by +16 mV at 37°C compared with 19°C. Consequently, the low availability of excitable Na+ channels at subphysiological temperatures resulted from channels being in the slow, inactivated state at the resting potential.

Sign in / Sign up

Export Citation Format

Share Document