Calcium movements in aortae from arthritic rats

Area of Science:

• Biochemistry
• Physiology
• Pharmacology

Background:

• Adjuvant arthritis in rats is a model for inflammatory conditions.
• Calcium homeostasis is crucial for vascular smooth muscle function.
• Altered calcium handling is implicated in vascular diseases.

Purpose of the Study:

• To investigate calcium (Ca++) content, uptake, influx, and efflux in aortae from arthritic rats.
• To determine the impact of arthritis on vascular calcium pathways.
• To assess the effect of verapamil on calcium handling in arthritic aortae.

Main Methods:

• Atomic absorption spectrometry for 40Ca content measurement.
• 45Ca isotope tracer studies for uptake, inflow, and outflow measurements.
• Vascular stimulation with high potassium and noradrenaline.
• Optical microscopy for histological examination.

Main Results:

• Arthritic rat aortae exhibited significantly higher 40Ca content compared to controls.
• Enhanced 45Ca uptake, inflow, and outflow were observed in arthritic aortae under basal and stimulated conditions.
• Verapamil inhibited stimulated 45Ca inflow but not basal uptake.
• No significant histological differences were found between normal and arthritic aortae.

Conclusions:

• Aortae from adjuvant arthritic rats have elevated intracellular Ca++ levels.
• This increase is attributed to enhanced Ca++ inflow via multiple pathways.
• The heightened intracellular Ca++ may reduce the dependence on extracellular calcium for agonist-induced contractions.