one of many contractile filaments that make up a striated muscle fiber (同)myofibrilla, sarcostyle
English Journal
Detection of pH Change in Cytoplasm of Live Myocardial Ischemia Cells via the ssDNA-SWCNTs Nanoprobes.
Liu R1, Liu L, Liang J, Wang Y, Wei Y, Gao F, Gao L, Gao X.Author information 1CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049, China.AbstractMyocardial ischemia is featured by a significant increase in the cytoplasm proton concentration, and such a proton change may be applied as an index for earlier ischemic heart disease diagnostics. But such a pH change in a live heart cell is difficult to monitor as a normal fluorescent probe cannot specifically transport into the cytoplasm of an ischemic cell. This is because the heart cell contains condensed myofibrils which are tight barriers for a normal probe to penetrate. We design fluorescent probes, single-strand DNA wrapped single-wall carbon nanotubes (ssDNA-SWCNTs), where the ssDNA is labeled by the dye molecule hexachloro-6-carboxyfluorescein (HEX). This nanoprobe could transport well into a live heart cell and locate in the cytoplasm to sensitively detect the intracellular pH change of myocardial ischemia. Briefly, protons neutralize the negative charges of nanoprobes in the cytoplasm. This will weaken the stability of nanoprobes and further tune their aggregation. Such aggregations induce the HEX of some nanoprobes condensed together and further result in their fluorescence quenching. The nanoprobes are advantaged in penetrating condensed myofibrils of the heart cell, and their fluorescence intensity is sensitive to the proton concentration change in the live cell cytoplasm. This new method may provide great assistance in earlier cardiopathy diagnosis in the future.
Analytical chemistry.Anal Chem.2014 Mar 5. [Epub ahead of print]
Myocardial ischemia is featured by a significant increase in the cytoplasm proton concentration, and such a proton change may be applied as an index for earlier ischemic heart disease diagnostics. But such a pH change in a live heart cell is difficult to monitor as a normal fluorescent probe cannot
Subcellular distribution of glycogen and decreased tetanic Ca2+ in fatigued single intact mouse muscle fibres.
Nielsen J1, Cheng AJ, Ortenblad N, Westerblad H.Author information 1Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Denmark;AbstractIn skeletal muscle fibres glycogen has been shown to be stored at different subcellular locations: (i) between the myofibrils (intermyofibrillar); (ii) within the myofibrils (intramyofibrillar); (iii) subsarcolemmal. Of these, intramyofibrillar glycogen has been implied as a critical regulator of sarcoplasmic reticulum Ca2+ release. The aim of the present study was to directly test how the decrease in cytoplasmic free Ca2+ ([Ca2+]i) during repeated tetanic contractions relates to the subcellular glycogen distribution. Single fibres of mouse flexor digitorum brevis muscles were fatigued with 70Hz, 350 ms tetani given at 2 s (high-intensity fatigue, HIF) or 10 s (low-intensity fatigue, LIF) intervals, while force and [Ca2+]i were measured. Stimulation continued until force decreased to 30% of its initial value. Fibres were then prepared for analyses of subcellular glycogen distribution by transmission electron microscopy. At fatigue, tetanic [Ca2+]i was reduced to 70±4% and 54±4% of the initial in HIF fibres (P<0.01, n=9) and LIF fibres (P<0.01, n=5), respectively. At fatigue, mean inter- and intramyofibrillar glycogen content was 60-75% lower than in rested control fibres (P<0.05), whereas subsarcolemmal glycogen was similar to control. Individual fibres showed a good correlation between the fatigue-induced decrease in tetanic [Ca2+]i and the reduction in inter- (P=0.051) and intramyofibrillar (P=0.0008) glycogen. In conclusion, the fatigue-induced decrease in tetanic [Ca2+]i, and hence force, is accompanied by major reductions in inter- and intramyofibrillar glycogen. The stronger correlation between decreased tetanic [Ca2+]i and reduced intramyofibrillar glycogen implies that sarcoplasmic reticulum Ca2+ release critically depends on energy supply from the intramyofibrillar glycogen pool.
The Journal of physiology.J Physiol.2014 Mar 3. [Epub ahead of print]
In skeletal muscle fibres glycogen has been shown to be stored at different subcellular locations: (i) between the myofibrils (intermyofibrillar); (ii) within the myofibrils (intramyofibrillar); (iii) subsarcolemmal. Of these, intramyofibrillar glycogen has been implied as a critical regulator of sa
Novel approaches to determine contractile function of the isolated adult zebrafish ventricular cardiac myocyte.
Dvornikov AV1, Dewan S, Alekhina OV, Pickett FB, de Tombe PP.Author information 1Loyola University Chicago, Stritch School of Medicine, United States;AbstractObjectives: The zebrafish (Danio rerio) has been used extensively in cardiovascular biology, but mainly for study of heart development. The relative ease of genetic manipulation could be the basis for this species to become a promising and cost-effective model system for the study of cardiac contractile biology. However, whether the zebrafish heart is an appropriate model system for questions pertaining to mammalian cardiac contractile structure-function relationships remains to be answered. Methods and Results: Myocytes were isolated from adult zebrafish hearts by enzymatic digestion, attached to carbon rods and twitch force and intracellular Ca2+ were measured. We observed modulation of twitch force, but not intracellular Ca2+, by both extracellular [Ca2+] and sarcomere length. In permeabilized cells/myofibrils, we found robust myofilament length dependent activation. Moreover, modulation of myofilament activation-relaxation and force redevelopment kinetics by varied Ca2+ activation levels resembled that found previously for mammalian myofilaments. Conclusions: We conclude that the zebrafish is a valid model system for the study of cardiac contractile structure-function relationships.
The Journal of physiology.J Physiol.2014 Mar 3. [Epub ahead of print]
Objectives: The zebrafish (Danio rerio) has been used extensively in cardiovascular biology, but mainly for study of heart development. The relative ease of genetic manipulation could be the basis for this species to become a promising and cost-effective model system for the study of cardiac contrac
… In terms of inactivation rate constant of myofibrilla Ca-ATPase, the thermal stability of Pacific myofibrillar protein was found to be comparable to those of Pacific mackerel and sardine but it became unstable at higher temperature and in an acjdic condition. …
What Does Myofibrilla Mean? Dictionary.com Word FAQs Dictionary.com presents 366 FAQs, incorporating some of the frequently asked questions from the past with newer queries. Differences Etymology/Origins Spelling Trivia ...
myofibril /myo·fi·bril/ (-fi´bril) muscle fibril; one of the slender threads of a muscle fiber, composed of numerous myofilaments. myofi´brillar my·o·fi·bril (m-f br l, -f b r l) n. One of the threadlike longitudinal fibrils occurring in a skeletal or ...