Related Experiment Video
Updated: Aug 14, 2026
11:00
Assessment of Sarcoplasmic Reticulum Calcium Reserve and Intracellular Diastolic Calcium Removal in Isolated Ventricular Cardiomyocytes
Published on: September 18, 2017
Sarcoplasmic reticulum function in murine ventricular myocytes overexpressing SR CaATPase
1Division of Cardiology, University of Utah Health Science Center, Salt Lake City 84132, USA.
Journal of Molecular and Cellular Cardiology
|February 17, 1999
Summary
Overexpression of sarcoplasmic reticulum (SR) CaATPase accelerates calcium decline in heart cells. This enhances SR calcium storage and slightly reduces the Na/Ca exchanger function.
Area of Science:
- Cardiovascular Physiology
- Molecular Cardiology
- Calcium Signaling
Background:
- Sarcoplasmic reticulum (SR) CaATPase is crucial for cardiac muscle relaxation.
- Altered SR CaATPase function impacts calcium homeostasis and contractility.
Purpose of the Study:
- To investigate the functional consequences of SR CaATPase overexpression on SR function and calcium (Ca2+) homeostasis.
- To assess the impact on intracellular Ca2+ ([Ca2+]i) transients, L-type Ca2+ currents (ICa.L), Na/Ca exchanger currents (INa/Ca), and SR Ca2+ content.
Main Methods:
- Utilized ventricular myocytes from wild type (WT) and transgenic (SRTG) mice overexpressing SR CaATPase.
- Employed voltage clamp techniques to measure [Ca2+]i transients, ICa.L, INa/Ca, and SR Ca2+ content.
- Used a rapid switcher device to isolate SR CaATPase function by inhibiting Na/Ca exchange.
Main Results:
- SR CaATPase overexpression significantly accelerated the decline of [Ca2+]i transients by 40%.
- SR Ca2+ content was significantly increased by 29% in SRTG myocytes.
- L-type Ca2+ channel function remained unchanged, while INa/Ca density showed a slight decrease (10%).
Conclusions:
- Overexpression of SR CaATPase markedly enhances SR Ca2+ reuptake, leading to faster cardiac relaxation.
- Increased SR Ca2+ content suggests improved calcium storage capacity.
- A compensatory downregulation of the Na/Ca exchanger may occur alongside SR CaATPase upregulation.
Related Concept Videos
01:34ATP Driven Pumps II: P-type Pumps
The P-type pumps are a large family of integral membrane transporter ATPases. They are divided into five major types based on substrate specificity, from I to V.
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
01:13Microscopic Anatomy of Skeletal Muscles
Skeletal muscle cells, also called muscle fibers, are distinctly elongated, multi-nucleated, slender biological units. They are packed with specialized structures designed to facilitate their primary function, which is contraction.
The muscle sarcolemma is a plasma membrane enclosing each muscle cell that conducts electrical signals called action potentials. The sarcolemma extends into the cell to form T-tubules, ensuring the neural impulses are uniformly distributed across the entire muscle...
The muscle sarcolemma is a plasma membrane enclosing each muscle cell that conducts electrical signals called action potentials. The sarcolemma extends into the cell to form T-tubules, ensuring the neural impulses are uniformly distributed across the entire muscle...
01:13Structure of Cardiac Muscles
Cardiac muscle, or myocardium, is a specialized type of muscle found exclusively in the heart. Its unique structural and functional characteristics enable the heart to perform its vital role of pumping blood throughout the body continuously and rhythmically. The cardiac muscle cells, or cardiomyocytes, possess an endomysium and perimysium but do not have an epimysium.
Compared to skeletal muscles, cardiac muscle cells are small and mostly have a single nucleus. Additionally, they are usually...
Compared to skeletal muscles, cardiac muscle cells are small and mostly have a single nucleus. Additionally, they are usually...
01:27Specialized Characteristics of Cardiac Muscles
The primary role of cardiac muscles is to propel blood throughout the cardiovascular system. The cardiac muscle cells, or cardiomyocytes, exhibit specialized characteristics that allow them to perform this function.
Cardiac muscle cells are smaller than skeletal muscles, averaging 10–20 mm in diameter and 50–100 mm in length. However, they have large energy demands for continuous contraction and relaxation. This energy is almost exclusively derived from aerobic metabolism of energy reserves in...
Cardiac muscle cells are smaller than skeletal muscles, averaging 10–20 mm in diameter and 50–100 mm in length. However, they have large energy demands for continuous contraction and relaxation. This energy is almost exclusively derived from aerobic metabolism of energy reserves in...
01:25Smooth Muscle Contraction
Smooth muscle contraction is a complex process vital for various bodily functions, from maintaining blood vessel tension to facilitating the movement of food through the digestive tract. Unlike striated muscles, smooth muscle contraction begins more slowly and lasts longer.
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...