Increased plasma serotonin in primary pulmonary hypertension

Evidence for 5-HT1-like receptor-mediated vasoconstriction in human pulmonary artery

1. The 5-hydroxytryptamine (5-HT) receptors mediating contraction of human isolated pulmonary artery rings were investigated. Responses to the agonists 5-carboximidotryptamine (5-CT, non-selective 5-HT1 agonist), sumatriptan (5-HT1D-like receptor agonist), 5-HT and 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT, 5-HT1A receptor agonist) were studied. Responses to 5-HT and sumatriptan in the presence of the antagonists, methiothepin (non-selective 5-HT1+2-receptor antagonist), ketanserin (5-HT2A receptor antagonist) and the novel antagonist, GR55562 (5-HT1D receptor antagonist) were also studied. 2. All agonists contracted human pulmonary artery ring preparations in the following order of potency 5-CT > 5-HT = sumatriptan > 8-OH-DPAT. Maximum responses to 5-HT, 5-CT and sumatriptan were not significantly different. 3. Methiothepin 1 nM and 10 nM, but not 0.1 nM reduced the maximum contractile responses to 5-HT but did not alter tissue sensitivity to 5-HT. Methiothepin 0.1 nM, 1 nM and 10 nM had a similar effect on responses to sumatriptan. 4. The 5-HT2A receptor antagonist ketanserin (10 nM, 100 nM and 1 microM) also reduced the maximum contractile response to both 5-HT and sumatriptan without affecting tissue sensitivity to these agonists. 5. The novel 5-HT1D receptor antagonist, GR55562, inhibited responses to 5-HT and sumatriptan in a true competitive fashion. 6. The results suggest that the human pulmonary artery has a functional population of 5-HT1D-like receptors which are involved in the contractile response to 5-HT.

Appetite-suppressant drugs and the risk of primary pulmonary hypertension. International Primary Pulmonary Hypertension Study Group

BACKGROUND

Recently, a cluster of patients was observed in France in whom primary pulmonary hypertension developed in patients exposed to derivatives of fenfluramine in appetite suppressants (anorexic agents), which are used for weight control. We investigated the potential role of anorexic agents and other suspected risk factors for primary pulmonary hypertension.

METHODS

In a case-control study, we assessed 95 patients with primary pulmonary hypertension from 35 centers in France, Belgium, the United Kingdom, and the Netherlands and 355 controls recruited from general practices and matched to the patients' sex and age.

RESULTS

The use of anorexic drugs (mainly derivatives of fenfluramine) was associated with an increased risk of primary pulmonary hypertension (odds ratio with any anorexic-drug use, 6.3; 95 percent confidence interval, 3.0 to 13.2). For the use of anorexic agents in the preceding year, the odds ratio was 10.1 (95 percent confidence interval, 3.4 to 29.9). When anorexic drugs were used to a total of more than three months, the odds ratio was 23.1 (95 percent confidence interval, 6.9 to 77.7). We also confirmed an association with several previously identified risk factors: a family history of pulmonary hypertension, infection with the human immunodeficiency virus, cirrhosis, and use of cocaine or intravenous drugs.

CONCLUSIONS

The use of anorexic drugs was associated with the development of primary pulmonary hypertension. Active surveillance for this disease should be considered, particularly since their use is expected to increase in the near future.