Pituitary gonadotropes transduce hormonal input into cytoplasmic calcium ([Ca(2+)](cyt)) oscillations that drive rhythmic exocytosis of gonadotropins. Using Calcium Green-1 and rhod-2 as optical measures of cytoplasmic and mitochondrial free Ca(2+), we show that mitochondria sequester Ca(2+) and tune the frequency of [Ca(2+)](cyt) oscillations in rat gonadotropes. Mitochondria accumulated Ca(2+...

The extracellular Ca(2+)-sensing receptor (CaR) is a widely expressed G-protein-coupled receptor that translates information about [Ca(2+)] in the extracellular milieu to the interior of the cell, usually via intracellular Ca(2+) signaling pathways. Using fura-2 imaging of cytoplasmic [Ca(2+)], we observed that HEK293 cells expressing CaR oscillated readily under conditions permissive for CaR a...

Introduction In the heart, excitation-contraction coupling (ECC) is a sequence of events that begins with membrane depolarization by an action potential (AP), followed by activation of voltage-gated Ca channels in the surface membrane, initiation of Ca release from the SR Ca store by CICR, and the resulting contraction. Most of our knowledge of the mechanistic details of ECC originates from stu...

Introduction In the heart, excitation-contraction coupling (ECC) is a sequence of events that begins with membrane depolarization by an action potential (AP), followed by activation of voltage-gated Ca channels in the surface membrane, initiation of Ca release from the SR Ca store by CICR, and the resulting contraction. Most of our knowledge of the mechanistic details of ECC originates from stu...

Introduction In the heart, excitation-contraction coupling (ECC) is a sequence of events that begins with membrane depolarization by an action potential (AP), followed by activation of voltage-gated Ca channels in the surface membrane, initiation of Ca release from the SR Ca store by CICR, and the resulting contraction. Most of our knowledge of the mechanistic details of ECC originates from stu...

Introduction In the heart, excitation-contraction coupling (ECC) is a sequence of events that begins with membrane depolarization by an action potential (AP), followed by activation of voltage-gated Ca channels in the surface membrane, initiation of Ca release from the SR Ca store by CICR, and the resulting contraction. Most of our knowledge of the mechanistic details of ECC originates from stu...

Introduction In the heart, excitation-contraction coupling (ECC) is a sequence of events that begins with membrane depolarization by an action potential (AP), followed by activation of voltage-gated Ca channels in the surface membrane, initiation of Ca release from the SR Ca store by CICR, and the resulting contraction. Most of our knowledge of the mechanistic details of ECC originates from stu...

Membrane proteins and membrane lipids are frequently organized in submicron-sized domains within cellular membranes. Factors thought to be responsible for domain formation include lipid-lipid interactions, lipid-protein interactions and protein-protein interactions. However, it is unclear whether the domain structure is regulated by other factors such as divalent cations. Here, we have examined...

A combination of the voltage-clamp and the intracellular dialysis techniques has been used to study the membrane potential dependence of the Nao-dependent Ca efflux in squid giant axons. In order to improve axon survival, experiments were carried out using internal solutions prepared with large impermeant organic anions and cations, which did not affect the operation of the Na/Ca exchange mecha...

Introduction In the heart, excitation-contraction coupling (ECC) is a sequence of events that begins with membrane depolarization by an action potential (AP), followed by activation of voltage-gated Ca channels in the surface membrane, initiation of Ca release from the SR Ca store by CICR, and the resulting contraction. Most of our knowledge of the mechanistic details of ECC originates from stu...