Related Experiment Video
Updated: Aug 2, 2026

Measurement of Calcium Fluctuations Within the Sarcoplasmic Reticulum of Cultured Smooth Muscle Cells Using FRET-based Confocal Imaging
Published on: June 20, 2016
[Intracellular calcium-dependent contractile effects of serotonin in the human umbilical artery]
Jesús Carlos Briones-Garduño1, Carlos Castillo-Henkel, Jorge Skiold López-Canales
1Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico, D. F. drcarlosbriones@hotmail.com
Background:
Absence of innervation is a hallmark of human umbilical vessels. Intervillous space blood flow is regulated by vasoactive substances and calcium dependent contractility, both in normal and pathological conditions such as preeclampsia-eclampsia.
Objective:
To obtain additional information on the intracellular calcium contractile effects of serotonin in human umbilical arteries.
Materials And Methods:
Umbilical arteries from normal pregnancies were dissected, cut in 5 mm rings and mounted in a temperature-controlled isolated organ chamber, using calcium-free Krebs solution. The contractile effects of serotonin, lantane, verapamil and cyclopiazonic acid were evaluated at different concentrations using a computer coupled biopac polygraph.
Results:
No differences in response were observed in the presence and absence of intracellular calcium. The positive contractile effects observed with serotonin were significantly decreased with repeated stimulation. An increase in the basal tone of the vessel was observed after calcium supplementation was added to the solution. This effect was minimized in the presence of verapamil and lantane. The contractile effects of serotonin in the calcium-free solution were not affected by the presence of cyclopiazonic acid.
Conclusions:
Serotonin contractile effects in the human umbilical artery depend mainly on intracellular calcium levels which favor the gradual entrance of this ion over time. Calcium influx induced by serotonin is possible through L and Non-L channels apparently insensitive to ciclopiozonic acid.
Related Concept Videos
Muscle Contraction
Muscle Contraction
Feedback Regulation of Calcium Concentration
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
Relaxation of Skeletal Muscles
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
Smooth Muscle Contraction
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...

