title: Substance P for evaluation of coronary endothelial function after cardiac transplantation.
abstract: The endothelium-dependent vasodilator substance P dilates normal and diseased coronary vessels in humans in vivo and produces a maximal response similar to that seen with intracoronary isosorbide dinitrate. Twelve cardiac transplant recipients underwent intracoronary infusion of substance P after routine annual investigations. All patients were well, with no evidence of rejection and with angiographically normal coronary arteries. Substance P was infused at 2 ml/min for 2 min into the coronary artery, starting at a dose of 1.4 pmol/min and increasing by doubling increments, and followed by isosorbide dinitrate (1 mg/min) infused over 2 min. Coronary artery diameter was measured in 23 vessel segments from 12 transplant recipients. The following doses were infused: saline solution (1 ml/min), substance P (0.7 [three patients], 1.4, 2.8, 5.6, 11.2, 22.4 pmol/min) and isosorbide dinitrate (1 mg/min). The mean percent increase in diameter (+/- SEM) in response to increasing doses of substance P was as follows: 0, 6.5 +/- 2.9%, 10.9 +/- 2.9%, 12.1 +/- 2.9%, 16.5 +/- 2.6%, 19.2 +/- 3.1% and 25.8 +/- 2.2%, respectively. Half maximal dilation was produced with 1.4 to 2.8 pmol/min of substance P; the maximal response (mean percent diameter change) was 22 +/- 2.5%. This was not significantly different from that achieved with isosorbide dinitrate. It is concluded that coronary endothelial function as assessed by response to substance P is preserved in cardiac transplant recipients with angiographically normal coronary arteries. Substance P may be a suitable agent for testing endothelial function in these patients.
authors.affiliation: Department of Cardiology, Harefield Hospital, Middlesex, England.
authors.forename: S S
authors.initials: SS
authors.lastname: Kushwaha
authors.forename: D C
authors.initials: DC
authors.lastname: Crossman
authors.forename: M
authors.initials: M
authors.lastname: Bustami
authors.forename: G J
authors.initials: GJ
authors.lastname: Davies
authors.forename: A G
authors.initials: AG
authors.lastname: Mitchell
authors.forename: A
authors.initials: A
authors.lastname: Maseri
authors.forename: M H
authors.initials: MH
authors.lastname: Yacoub
mesh_terms: D017023:Coronary Angiography; D003331:Coronary Vessels / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology*; D016027:Heart Transplantation / Q000502:physiology*; D006801:Humans; D007548:Isosorbide Dinitrate; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000096:biosynthesis; D013373:Substance P / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*
chemical_list: D009569:Nitric Oxide; D013373:Substance P; D007548:Isosorbide Dinitrate