Alterations in basal and serotonin-stimulated calcium permeability and vasoconstriction in atherosclerotic aorta.

Abstract

Hypersensitivity to vasoactive stimuli, a common finding in atherosclerotic arteries, is thought to play an important role in the pathology of arterial and coronary vasospasm and may be a factor in myocardial ischemia and infarction. While this phenomenon is well documented, the underlying mechanism is unknown. The present study used isometric force measurements coupled with <5 Ca 2+ and Fura 2-AM techniques in aortic smooth muscle to probe transmembrane calcium movements and cytosolic calcium levels in an attempt to determine their relation to altered vasomotion in a rabbit model of dietary atherosclerosis. Following 10 weeks of cholesterol feeding (2%), basal (unstimulated) calcium influx was augmented 1.5-fold in atherosclerotic segments with no change in basal calcium efflux. Serotonin-stimulated calcium uptake was increased 1.9-fold in atherosclerotic segments and was accompanied by a fivefold increase in serotonin vasocon-

Vascular effects of deletion of melanocortin-4 receptors in rats

“…Briefly, two tungsten wires were inserted into the lumen of the arteries and fixed to a force transducer and a micrometer. Arteries were bathed in a physiological salt solution as previously described (Stepp and Tulenko ). Arterial viability was determined using a potassium rich solution (40 mmol/L).…”

Role of local production of endothelium-derived nitric oxide on cGMP signaling and S-nitrosylation

“…Concentration-response curves were then constructed to phenylephrine (PE, 10 Ϫ9 to 10 Ϫ5 M). To assess endothelial-dependent vasodilation, vessels were precontracted with a submaximal concentration of PE (10 Ϫ6 M) before the serial application of the endothelium-dependent agonist, ACh (10 Ϫ9 to 10 Ϫ5 M) (43). Statistical analysis.…”

Influence of serum cholesterol on atherogenesis and intimal hyperplasia after angioplasty: inhibition by amlodipine

“…Calcium permeability in SMCs was assessed in ring segments using a 45 Ca 2ϩ uptake protocol as described previously (57). Briefly, because Ca 2ϩ uptake in aortic SMCs in ring segments is linear over a 5-min period (57), segments were incubated in PSS containing 45 Ca 2ϩ (2.5 Ci/ml) at 37°C for 3 min and blotted lightly.…”

“…Briefly, because Ca 2ϩ uptake in aortic SMCs in ring segments is linear over a 5-min period (57), segments were incubated in PSS containing 45 Ca 2ϩ (2.5 Ci/ml) at 37°C for 3 min and blotted lightly. Uptake was terminated by transferring the segments to ice-cold calcium-free PSS containing 2 mM EGTA vigorously agitated with a stream of 100% O2 for 60 min.…”