The effect of caffeine on calcium efflux and calcium translocation in skeletal and visceral muscle

1975 ◽  
Vol 63 (1) ◽  
pp. 131-142
Author(s):  
H. Huddart ◽  
A. J. Syson

1. KCl-induced depolarization resulted in a large stimulation of the 45Ca efflux from both cockroach skeletal muscle and rat ileal smooth muscle. 2. Caffeine (10 mM) induced a large stimulation of 45Ca efflux from skeletal muscle, but a fall in the efflux from ileal muscle, especially if the efflux was previously stimulated by KCl depolarization. 3. Caffeine inhibited calcium uptake by skeletal muscle mitochondria and sarcoplasmic reticulum, was without effect on ileal muscle mitochondria, but significantly increased caclium binding by ileal muscle membrane vesicular preparations. 4. The induction of contractures and stimulation of 45Ca efflux in skeletal muscle by caffeine are clearly related to inhibition of intracellular calcium binding by the sarcoplasmic reticulum and mitochondria. 5. The relaxation of ileal muscle by caffeine and the inhibition of fibre calcium efflux correlate well with caffeine enhancement of intracellular calcium binding. These experiments suggest that the membrane vesicular compartment may be the main agency centrally involved in fibre calcium regulation in this muscle during the contraction-relaxation cycle.

1970 ◽  
Vol 48 (12) ◽  
pp. 1332-1338 ◽  
Author(s):  
K. Wrogemann ◽  
M. C. Blanchaer ◽  
B. E. Jacobson

Skeletal muscle mitochondria were isolated in the presence and absence of the proteinase Nagarse from dystrophic hamsters of the BIO 14.6 strain, aged 45–196 days, and from normal hamsters. Mitochondria from the dystrophic animals prepared by glass-on-glass homogenization without Nagarse in 0.25 M sucrose – 1 mM EDTA, pH 7.4, did not differ from normal in their respiratory rate or capacity for oxidative phosphorylation. However, these functions were subnormal in mitochondria isolated with Nagarse from the same animals, both in the presence and absence of albumin. Respiration measured with an O2 electrode was reduced by 50–70% and the stimulation of O2 uptake normally seen after ADP addition was minimal or absent. This was most marked in mitochondria from young hamsters about 65 days old with muscle necrosis. The defect was ameliorated by addition to the Polarographie test system of an ATP trap or of Mg2+, one of the trap constituents. This ion, when added to the defective mitochondria prior to ADP and substrate, restored respiration and oxidative phosphorylation to values that did not differ significantly from those found with skeletal muscle mitochondria of normal hamsters.


Endocrinology ◽  
2008 ◽  
Vol 149 (12) ◽  
pp. 6262-6271 ◽  
Author(s):  
Ana Paula Arruda ◽  
Luisa A. Ketzer ◽  
Mariana Nigro ◽  
Antonio Galina ◽  
Denise P. Carvalho ◽  
...  

Brown adipose tissue (BAT) is involved in rat and mice thermoregulation, and heat produced by BAT depends on the concerted action of thyroid hormones and catecholamines. Little is known about cold-induced thermogenesis in mammals that have little or no BAT, such as rabbits. In these animals, thermogenesis primarily occurs in skeletal muscle. In this work, we have studied the effect of cold acclimation (4 C for 10 d) in normal and hypothyroid rabbits. It is known that hypothyroid rats die after a few hours of cold exposure. We now show that, different from rats, hypothyroid rabbits sustain their body temperature and survive after 10 d cold exposure. When compared with rabbits kept at room temperature, the muscles of cold-exposed rabbits showed a dark red color characteristic of oxidative muscle fibers. According to this pattern, we observed that in both normal and hypothyroid rabbits, cold exposure promotes an increase in oxygen consumption by skeletal muscle mitochondria. Moreover, in red muscle, cold acclimation induces an increase in the expression and activity of sarcoplasmic reticulum Ca2+ ATPase isoform 1 (SERCA1), one of the muscle enzymes involved in heat production. We conclude that rabbit cold tolerance is probably related to increased muscle oxidative metabolism and heat production by SERCA1 and that these changes are not completely dependent on normal thyroid function.


1986 ◽  
Vol 87 (2) ◽  
pp. 271-288 ◽  
Author(s):  
P Volpe ◽  
E W Stephenson

Isometric force and 45Ca efflux from the sarcoplasmic reticulum were measured at 19 degrees C in frog skeletal muscle fibers skinned by microdissection. After Ca2+ loading, application of the ionophores monensin, an Na+(K+)/H+ exchanger, or gramicidin D, an H+ greater than K+ greater than Na+ channel-former, evoked rapid force development and stimulated release of approximately 30% of the accumulated 45Ca within 1 min, whereas CCCP (carbonyl cyanide pyruvate p-trichloromethoxyphenylhydrazone), a protonophore, and valinomycin, a neutral, K+-specific ionophore, did not. When monensin was present in all bathing solutions, i.e., before and during Ca2+ loading, subsequent application failed to elicit force development and to stimulate 45Ca efflux. 5 min pretreatment of the skinned fibers with 50 microM digitoxin, a permeant glycoside that specifically inhibits the Na+,K+ pump, inhibited monensin and gramicidin D stimulation of 45Ca efflux; similar pretreatment with 100 microM ouabain, an impermeant glycoside, was ineffective. Monensin stimulation of 45Ca efflux was abolished by brief pretreatment with 5 mM EGTA, which chelates myofilament-space calcium. These results suggest that: monensin and gramicidin D stimulate Ca2+ release from the sarcoplasmic reticulum that is mediated by depolarization of the transverse tubules, which seal off after sarcolemma removal and form closed compartments; a transverse tubule membrane potential (myofilament space-negative) is maintained and/or established by the operation of the Na+,K+ pump in the transverse tubule membranes and is sensitive to the permeant inhibitor digitoxin; the transverse tubule-mediated stimulation of 45Ca efflux appears to be entirely Ca2+ dependent.


1991 ◽  
Vol 274 (2) ◽  
pp. 565-573 ◽  
Author(s):  
F Cardellach ◽  
T F Taraschi ◽  
J S Ellingson ◽  
C D Stubbs ◽  
E Rubin ◽  
...  

The effect of long-term ethanol intake on the structural and functional characteristics of rat skeletal-muscle mitochondria and sarcoplasmic reticulum was investigated. Functionally, skeletal-muscle mitochondria were characterized by a high respiratory control index and ADP/O ratio and a high State-3 respiration rate with different substrates. These parameters were not significantly different in preparations from control and ethanol-fed rats, except for a small increase in the rate of oxidation of alpha-oxoglutarate/malate in the latter. In submitochondrial particles from the two groups of animals there was no significant difference in cytochrome content, ATPase activity or the activity of respiratory-chain complexes. Mitochondrial membranes from untreated and ethanol-fed rats showed no difference in the baseline e.s.r. order parameter, and both preparations were equally sensitive to disordering by ethanol in vitro. Similarly, sarcoplasmic-reticulum preparations were not significantly affected by long-term ethanol feeding with respect to Ca2(+)-ATPase activity or in baseline order parameter and susceptibility to membrane disordering by ethanol in vitro. These membranes were also equally sensitive to degradation by exogenous phospholipase A2. Ethanol feeding did not alter the class composition of mitochondrial or sarcoplasmic-reticulum membrane phospholipids, nor the acyl composition of individual phospholipid classes. Specifically, the changes in acyl composition that characteristically occur in liver microsomal phosphatidylinositol and liver mitochondrial cardiolipin were not observed in the corresponding phospholipids from skeletal-muscle membranes. In experiments where membrane preparations from liver and skeletal muscle from the same ethanol-fed animals were compared, the liver membranes developed membrane tolerance, with the muscle membranes retaining normal sensitivity to disordering effects by ethanol. It is concluded that: (a) different tissues from the same animals differ in their susceptibility to ethanol; (b) the tissue-specific lack of development of membrane tolerance correlates with a lack of chemical changes in the phospholipids and with a retention of normal function of mitochondria and sarcoplasmic reticulum; (c) effects of chronic ethanol intake on muscle function are not due to a defect in the mitochondrial energy supply.


Author(s):  
Joachim R. Sommer ◽  
Nancy R. Wallace

After Howell (1) had shown that ruthenium red treatment of fixed frog skeletal muscle caused collapse of the intermediate cisternae of the sarcoplasmic reticulum (SR), forming a pentalaminate structure by obi iterating the SR lumen, we demonstrated that the phenomenon involves the entire SR including the nuclear envelope and that it also occurs after treatment with other cations, including calcium (2,3,4).From these observations we have formulated a hypothesis which states that intracellular calcium taken up by the SR at the end of contraction causes the M rete to collapse at a certain threshold concentration as the first step in a subsequent centrifugal zippering of the free SR toward the junctional SR (JSR). This would cause a) bulk transport of SR contents, such as calcium and granular material (4) into the JSR and, b) electrical isolation of the free SR from the JSR.


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