Biomedical subjects

J Gellman

Publications and source records attributed to J Gellman.

4 recordsLinked to original sources

PubMed1993

Potentiation of the vasospastic response to angioplasty by pretreatment with fluoxetine. A study in the atherosclerotic rabbit.

There is evidence that angioplasty-induced vasospasm is mediated by serotonin (5-hydroxytryptamine [5-HT]) release from platelets. We tested the hypothesis that pretreatment of the atherosclerotic rabbit with fluoxetine, a platelet-uptake inhibitor of 5-HT, would reduce vasospasm after balloon angioplasty. Short-term administration of fluoxetine reduced platelet 5-HT uptake to 4% of baseline. Daily administration of fluoxetine for 7 days reduced whole-blood 5-HT levels to 28% of baseline. Thus, fluoxetine inhibited platelet 5-HT uptake in this model as predicted. Contrary to our expectations and despite the substantial reduction in whole-blood 5-HT levels, pretreatment with fluoxetine for 1 week resulted in augmentation of angioplasty-induced vasospasm in atherosclerotic rabbits. Intraperitoneal administration of fluoxetine produced vasoconstriction in normal rabbits that was augmented by 5-HT and not reversed with LY53857, a specific serotonin receptor antagonist. We postulate that this new observation is probably a result of the inhibition of the clearance mechanism for serotonin, with resultant enhancement of the effect of serotonin released by the activated platelets that are deposited on the vessel wall surface at the time of angioplasty. A direct effect of fluoxetine on serotonergic receptors is a second possible mechanism for the observed effect.

Angioplasty↗

PubMed1991

Effect of lovastatin on intimal hyperplasia after balloon angioplasty: a study in an atherosclerotic hypercholesterolemic rabbit.

Restenosis, the major limitation of balloon angioplasty, is the result of intimal hyperplasia after the procedure. Lovastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) inhibitor, may influence intimal hyperplasia by lowering serum cholesterol and by blocking deoxyribonucleic acid (DNA) synthesis. To determine whether lovastatin reduces intimal hyperplasia, a prospective, randomized blinded study was performed in 60 atherosclerotic New Zealand White male rabbits. Atherosclerosis was produced by air desiccation injury followed by a 28 day diet of 2% cholesterol and 6% peanut oil that was terminated before balloon angioplasty was performed. Angioplasty could not be performed in 14 rabbits with bilateral femoral artery occlusion, and in one rabbit the procedure was a technical failure. Forty-five rabbits underwent balloon angioplasty performed with use of a 2.5-mm balloon inflated to 10 atm for three 1 min dilations at 1 min intervals. Seven rabbits died during the procedure. Thirty-eight rabbits were randomized to either a lovastatin group (6 mg/kg body weight per day) or a control group. Angioplasty was performed on all patent vessels (n = 54); the procedure was bilateral in 16 rabbits and unilateral in 22. Fifteen lovastatin-treated and 15 control rabbits survived 39 days after angioplasty and were then killed. Angiograms, obtained before and 10 min and 39 days after balloon angioplasty, were read with use of electronic calipers by two observers who had no knowledge of treatment data. After the rabbits were killed, vessels were pressure perfused using a standardized protocol to maintain in vivo dimensions for blinded quantitative histologic analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗

PubMedDate not supplied

Cholesterol, cholesterol lowering, and endothelial function.

A strong relationship between hypercholesterolemia and atherosclerosis has been established through epidemiological, experimental, and clinical trial data. Traditional theories on the pathophysiology of this relationship involve the deposition, modification, and cellular uptake of cholesterol, and the release of inflammatory and growth factors resulting in smooth muscle cell proliferation and collagen matrix production. The vasculature has recently been found to be an active and complex organ, with the endothelium playing a controlling role in vascular tone, lipid breakdown, thrombogenesis, inflammation, and vessel growth. In the presence of risk factors such as hypercholesterolemia, the endothelium promotes vasoconstriction, monocyte and platelet adhesion, thrombogenesis, and growth factor release. A high-fat diet also directly impairs endothelial function and increases coagulation factors. Endothelial dysfunction is associated with decreased availability of the predominant vasodilator nitric oxide, possibly by increased destruction by oxygen free radicals. This dysfunctional state appears before the earliest anatomic evidence of atherosclerosis and may represent an important initial step in its development. Several studies have shown improvements in endothelial function with cholesterol lowering in both normal individuals and those with coronary heart disease. Short-term improvements in endothelial-dependent vasodilation and adhesion molecule expression have also been reported with antioxidant therapy. These observations suggest that atherosclerosis is at least in part caused by endothelial dysfunction that favors cellular proliferation. This new understanding helps to explain the early and substantial reductions in major cardiovascular events associated with cholesterol lowering.

Animals↗

PubMedDate not supplied

Effects of serotonin-receptor blockade on angioplasty-induced vasospasm in an atherosclerotic rabbit model.

Vasospasm occurs both in patients and animal models after angioplasty and may be associated with early closure of the dilated vessel. To investigate the mechanism of angioplasty-induced vasospasm, the effect of serotonin-receptor blockade with two serotonin2 (S2) antagonists, LY53857 and sergolexole, was examined in rabbits with focal femoral artery atherosclerosis. In preliminary studies, local infusion of 1-100 micrograms serotonin caused significant femoral artery vasoconstriction (p less than 0.05) in both normal and atherosclerotic rabbits. There was no significant difference in the degree of vasoconstriction induced by equal doses of serotonin in normal and atherosclerotic animals. Infusion of 10 micrograms serotonin produced a 23 +/- 5% decrease in luminal diameter in atherosclerotic femoral arteries. This was blocked by pretreatment with both S2 inhibitors given separately in different animals before serotonin infusion (p less than 0.002). In contrast, LY53857 (sergolexole was not tested) had no significant effect on phenylephrine-induced vasoconstriction, confirming its specificity as an S2-receptor antagonist. Balloon angioplasty of atherosclerotic vessels caused a significant increase in vessel diameter at the angioplasty site (45% increase from baseline diameter, p less than 0.05). This was associated with significant luminal narrowing both proximal (21% reduction from baseline, p less than 0.05) and distal (17% reduction from baseline, p less than 0.03) to the angioplasty site. These proximal and distal changes are most likely due to vasospasm, as there was no histological evidence of thrombus or dissection at these sites to explain the luminal narrowing. Pretreatment of animals with 10 mg LY53857 or 20 mg sergolexole blocked the proximal vasospasm (2.6 +/- 0.4 before versus 2.2 +/- 0.1mm after angioplasty for LY53857, 2.1 +/- 0.4 before versus 2.1 +/- 0.4 mm after angioplasty for sergolexole; p = NS). Treatment with 20 mg LY53857 inhibited both proximal (2.3 +/- 0.1 before versus 2.2 +/- 0.2 mm after angioplasty, p = NS) and distal (1.7 +/- 0.1 before versus 1.6 +/- 0.2 mm after angioplasty, p = NS) vasospasm after angioplasty. Proximal (2.3 +/- 0.5 before versus 2.5 +/- 0.3 mm after) and distal (1.7 +/- 0.2 before versus 1.7 +/- 0.4 mm after) vasospasm was also prevented by pretreatment with 40 mg sergolexole.(ABSTRACT TRUNCATED AT 400 WORDS)

Angioplasty, Balloon↗