Divergent effects of serotonin on coronary-artery dimensions and blood flow in patients with coronary atherosclerosis and control patients

Article Abstract:

To investigate a possible role for serotonin, a substance released from platelets (blood cells essential for clotting), in coronary artery disease, seven patients with coronary artery atherosclerosis (narrowing of the arteries because of the deposition of fatty plaque in the lumen) and seven control patients were studied. Under angiographic guidance (in which X-rays are taken of the vessels after a dye is injected), several variables related to blood flow within a coronary artery were measured before and after the infusion of serotonin or ketanserin (a substance that blocks the effects of serotonin by interfering with its molecular receptor). Results showed that the coronary arteries of patients without atherosclerosis responded to serotonin by dilating, with an increase in cross-sectional area of 52 percent at the highest dose. This was associated with a 58 percent increase in the coronary blood flow. However, arteries of patients with atherosclerotic lesions constricted in response to serotonin, decreasing their cross-sectional area by an average of 64 percent. This response was associated with decreased coronary blood flow. Hypotheses are presented concerning the ways these effects might be mediated: data from the ketanserin trials helped determine which subtypes of serotonin receptor mediate the vasodilating and vasoconstrictive effects. It seems likely that vasodilation in the nondiseased arteries is the consequence of type 1 receptor activation, while vasoconstriction in damaged atherosclerotic arteries results from activation of type 2 receptors. One clinical implication of these results is that serotonin and other substances derived from platelets may play a role in some acute coronary ischemic disorders (disorders where the heart does not receive enough blood). Treatment could include drugs that antagonize type 2 serotonin receptors. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Complications and side effects, Coronary heart disease, Coronary arteries, Serotonin

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Preinfarction angina as a predictor of more rapid coronary thrombolysis in patients with acute myocardial infarction

Article Abstract:

People whose heart attacks are preceded by chest pain tend to have less damage to the heart and respond more quickly to anti-clotting therapy than people without preceding chest pain. Researchers administered anti-clotting therapy, including tissue plasminogen activator (t-PA), to 14 people who had chest pain during the week before a heart attack and to 9 people who did not have such pain before a heart attack. After beginning t-PA, circulation returned to previously blocked coronary arteries in an average of 27 minutes in the people with preceding chest pain and 48 minutes in the people without chest pain. As indicated by measures of the enzyme creatine kinase in the blood, the amount of damaged heart tissue was greater in people who had not had chest pain. This lesser degree of damage is probably due to the more rapid return of circulation to the heart.

Heart attack, Thrombolytic therapy

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