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;...

Smaller Ca2+ transients and systolic dysfunction in heart failure (HF) can be largely explained by reduced total sarcoplasmic reticulum (SR) Ca2+ content ([Ca]SRT). However, it is unknown whether low [Ca]SRT is manifest as reduced: (1) intra-SR free [Ca2+] ([Ca2+]SR), (2) intra-SR Ca2+ buffering, or (3) SR volume (as percentage of cell volume). Here we assess these possibilities in a well-chara...

To determine the effects of insulin on intracellular calcium and platelet aggregatory responses in hypertensive subjects with insulin resistance, we measured insulin sensitivity in terms of glucose disposal rate (GDR) by the hyperinsulinemic euglycemic clamp technique (GC) in 14 non-diabetic untreated hypertensive subjects, and determined basal ([Ca2+];) and thrombin-stimulated (T-[Ca2+];) plat...

BACKGROUND There is growing evidence suggesting involvement of L-type voltage-gated Ca2+ channels (VGCCs) in purinergic signaling mechanisms. However, detailed interplay between VGCCs and P2X receptors in intracellular Ca2+ mobilization is not well understood. This study examined relative contribution of the Ca2+ entry mechanisms and induced by this entry Ca2+ release from the intracellular sto...

The sarcolemmal Na(+)-Ca2+ exchanger is regulated by intracellular Ca2+ at a high affinity Ca2+ binding site separate from the Ca2+ transport site. Previous data have suggested that the Ca2+ regulatory site is located on the large intracellular loop of the Na(+)-Ca2+ exchange protein, and we have identified a high-affinity 45Ca2+ binding domain on this loop (Levitsky, D. O., D. A. Nicoll, and K...

Over the past two decades, a significant contribution to the pathophysiology of heart failure (HF) has been attributed to alterations of Ca2+ handling, which has been observed in myocytes isolated from failing hearts. Initially, a reduced Ca2+ transient amplitude due to a reduced Ca2+ reuptake rate by SERCA and enhanced extrusion of Ca2+ to the extracellular space by the Na+/Ca2+ exchanger had ...