Signaling Microdomains Regulate Inositol 1,4,5-Trisphosphate-Mediated Intracellular Calcium Transients in Cultured Neurons

We have investigated the subcellular distribution and identity of inositol trisphosphate (InsP3)-sensitive calcium stores in living Limulus ventral photoreceptor cells, where light and InsP3 are known to raise intracellular calcium. We injected ventral photoreceptor cells with the photoprotein aequorin and viewed its luminescence with an image intensifier. InsP3 only elicited detectable aequorin luminescence when injected into the light-sensitive rhabdomeral (R)-lobe where aequorin luminescence induced by light was also confined. Calcium stores released by light and InsP3 are therefore localized to the R-lobe. Within the R-lobe, InsP3-induced aequorin luminescence was further confined around the injection site, due to rapid dilution and/or degradation of injected InsP3. Prominent cisternae of smooth endoplasmic reticulum are uniquely localized within the cell beneath the microvillar surface of the R-lobe (Calman, B., and S. Chamberlain, 1982, J. Gen. Physiol., 80:839-862). These cisternae are the probable site of InsP3 action.

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Tension and Intracellular Calcium Transients of Activated Ferret Ventricular Muscle in Response to Step Length Changes

Mechanism of Myofilament Sliding in Muscle Contraction - Advances in Experimental Medicine and Biology ◽

10.1007/978-1-4615-2872-2_57 ◽

1993 ◽

pp. 639-648 ◽

Cited By ~ 5

Author(s):

Yasutake Saeki ◽

Satoshi Kurihara ◽

Kenichi Hongo ◽

Etsuko Tanaka

Keyword(s):

Intracellular Calcium ◽

Step Length ◽

Calcium Transients ◽

Ventricular Muscle ◽

Length Changes

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Caffeine attenuates contraction-induced diminutions of the intracellular calcium transient in mouse lumbrical muscle ex vivo

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2018-0658 ◽

2019 ◽

Vol 97 (5) ◽

pp. 429-435 ◽

Cited By ~ 2

Author(s):

Ian C. Smith ◽

Rene Vandenboom ◽

A. Russell Tupling

Keyword(s):

Skeletal Muscle ◽

Intracellular Calcium ◽

Calcium Release ◽

Ex Vivo ◽

Calcium Transient ◽

Calcium Transients ◽

Inotropic Effects ◽

Intracellular Calcium Transient ◽

Lumbrical Muscle ◽

Lumbrical Muscles

The amount of calcium released from the sarcoplasmic reticulum in skeletal muscle rapidly declines during repeated twitch contractions. In this study, we test the hypothesis that caffeine can mitigate these contraction-induced declines in calcium release. Lumbrical muscles were isolated from male C57BL/6 mice and loaded with the calcium-sensitive indicator, AM-furaptra. Muscles were then stimulated at 8 Hz for 2.0 s in the presence or absence of 0.5 mM caffeine, at either 30 °C or 37 °C. The amplitude and area of the furaptra-based intracellular calcium transients and force produced during twitch contractions were calculated. For each of these measures, the values for twitch 16 relative to twitch 1 were higher in the presence of caffeine than in the absence of caffeine at both temperatures. We conclude that caffeine can attenuate contraction-induced diminutions of calcium release during repeated twitch contractions, thereby contributing to the inotropic effects of caffeine.

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