The peritrich ciliate Vorticella sp. exhibits cellular contraction of an all-or-nothing type in response to a mechanical stimulus. Many authors have suggested that the contraction may be controlled by the cytosolic level of Ca2+, since glycerol-extracted Vorticella contracts when Ca2+ is added to the external solution. However, no direct evidence for the increase in cytosolic [Ca2+] has yet bee...

The demonstration that F1FO (F)-ATP synthase and adenine nucleotide translocase (ANT) can form Ca2+-activated, high-conductance channels in the inner membrane of mitochondria from a variety eukaryotes led to renewed interest permeability transition (PT), increase mediated by PT pore (PTP). is Ca2+-dependent mitochondrial whose function underlying molecular mechanisms have challenged scientists ...

Bovine chromaffin-granule ghosts accumulate 45Ca2+ in a temperature- and osmotic-shock-sensitive process; the uptake is saturable, with Km 38 microM and Vmax. 28 nmol/min per mg at 37 degrees C. Entry occurs by exchange with Ca2+ bound to the inner surface of the membrane. It is inhibited non-competitively by Na+, La3+ and Ruthenium Red (Ki 10.7 mM, 7 microM and 2 microM respectively), and comp...

The regulatory protein phospholamban exerts a physiological inhibitory effect on the sarcoplasmic reticulum (SR) Ca2+ pump that is relieved with phosphorylation. We have studied the subcellular properties of intracellular Ca2+([Ca2+]i) transients in ventricular myocytes isolated from wild-type (WT) and phospholamban-deficient (PLB-KO) mice. In PLB-KO myocytes, steady-state twitch [Ca2+]itransie...

The amount of Ca2+ released from the sarcoplasmic reticulum (SR) is a principal determinant of cardiac contractility. Normally, the SR Ca2+ stores are mobilized through the mechanism of Ca2+-induced Ca2+ release (CICR). In this process, Ca2+ enters the cell through plasmalemmal voltage-dependent Ca2+ channels to activate the Ca2+ release channels in the SR membrane. Consequently, the control of...

Increased mitochondrial Ca2+ drives the adaptive metabolic boost observed during early phases of ER stress Increases in mitochondrial respiration and ATP production are often consequences of increases in mitochondrial Ca2+ (Green and Wang, 2010). In order to determine whether early phases of ER stress induced by tunicamycin increased mitochondrial Ca2+ , we treated cells expressing cytosolic or...

Microprocessor-controlled changes of [free Ca2+] at the outer surface of the sarcoplasmic reticulum (SR) wrapped around individual myofibrils of a skinned canine cardiac Purkinje cell and aequorin bioluminescence recording were used to study the mechanism of Ca2+-induced release of Ca2+ from the SR. This Ca2+ release is triggered by a rapid increase of [free Ca2+] at the outer surface of the SR...

Airway smooth muscle cell contraction is regulated by changes in intracellular Ca2+ concentration ([Ca2+]i) and the responsiveness of the airway smooth muscle cell to this Ca2+. The mechanism controlling [Ca2+]i primarily involves agonist-induced release of Ca2+ from internal stores to generate Ca2+ oscillations. The extent of contraction correlates with the persistence and frequency of these C...

Abstract Introduction Long QT Syndrome (LQTS) is a major inherited arrhythmia syndrome that can cause sudden cardiac death. Using genome sequencing in human patients, mutations the ubiquitous calcium (Ca2+) sensor protein calmodulin (CaM) have been associated to LQTS. CaM an ion channel regulator and modulate activity of voltage-gated (Cav1.2) Ca2+/CaM-dependent kinase II (CaMKIIδ), involved mu...

The Ca2+ indicator photoprotein, aequorin, was used to estimate and monitor intracellular Ca2+ levels in Limulus ventral photoreceptors during procedures designed to affect Na+/Ca2+ exchange. Dark levels of [Ca2+]i were estimated at 0.66 +/- 0.09 microM. Removal of extracellular Na+ caused [Ca2+]i to rise transiently from an estimated 0.5-0.6 microM in a typical cell to approximately 21 microM;...