Abstract
Calcium release from the sarcoplasmic reticulum (SR) in cardiac muscle
occurs through a specialised release channel, the ryanodine receptor,
RyR, via the process of Ca-induced Ca release (CICR). The open probability
of the RyR is increased by elevation of cytoplasmic Ca concentration
(Ca$^2+$(i)). However, in addition to Ca, other modulators
affect the RyR open probability. Agents which increase the RyR opening
during systole produce a transient increase of systolic Ca$^2+$(i)
followed by a return to the initial level due to a compensating decrease
of SR Ca content. Increasing RyR opening during diastole decreases
SR Ca content and thereby decreases systolic Ca$^2+$(i). We
therefore conclude that potentiation of RyR opening will, if anything,
decrease systolic Ca$^2+$(i). The effects of specific examples
of modulators of the RyR, such as phosphorylation, metabolic changes,
heart failure and polyunsaturated fatty acids, are discussed.
- 15110148
- adaptation,
- animals,
- arrhythmia,
- calc,
- calcium
- calcium,
- channel
- channel,
- channels,
- conduction
- contraction,
- fluid,
- gating,
- gov't,
- heart
- heart,
- humans,
- intracellular
- ion
- ium
- muscle,
- myocardial
- myocardium,
- non-u.s.
- physiological,
- receptor
- release
- research
- reticulum,
- ryanodine
- sarcoplasmic
- skeletal,
- support,
- system,
Users
Please
log in to take part in the discussion (add own reviews or comments).