Related Experiment Video
Updated: Jul 17, 2026
Human Internal Mammary Artery (IMA) Transplantation and Stenting: A Human Model to Study the Development of In-Stent Restenosis
Published on: May 9, 2012
Vasorelaxant effect of iloprost on isolated human internal mammary artery
M O Serbest1, B C Soner, O N Sariosmanoglu
1Department of Cardiovascular Surgery, School of Medicine, Dokuz Eylul University, 35340, Balcova, Izmir, Turkey.
In this study, vasodilator effect of iloprost on KCl-induced contraction in human internal mammary artery (IMA) was studied and compared with other vasodilators papaverin and diltiazem. Ring segments of IMA were studied in organ baths for measurement of isometric tension. After the tissues has reached their baseline tension, precontraction was induced by 100 mm KCl and cumulative concentration-relaxation was measured by the application of iloprost (10(-9)-10(-6) m), papaverine (10(-5)-10(-4) m), diltiazem (10(-9)-10(-4) m) or ethanol; a solvent for iloprost; alone. The maximal relaxation of IMA segments to iloprost was 13.5 +/- 2.2%. Iloprost caused significantly limited relaxation when compared with papaverin (106.0 +/- 2.9%) and diltiazem (93.6 +/- 2.5%) (P < 0.001). Papaverin produced the greatest maximal relaxation to KCl-induced contraction of IMA. The potency of iloprost (-log EC(50) = 6.59 +/- 0.19) was significantly higher than those of papaverine (-log EC(50) = 4.21 +/- 0.11) and diltiazem (-log EC(50) = 5.63 +/- 0.06) (P < 0.001). In addition, -log EC(50) of diltiazem was significantly greater than papaverin (P < 0.001). Iloprost appears to be more potent than those of papaverine and diltiazem but it was inefficient in maximal inhibition on KCl-induced contraction. Iloprost may have little benefit in KCl-related vasoconstriction on human IMA segments.
In this study, vasodilator effect of iloprost on KCl-induced contraction in human internal mammary artery (IMA) was studied and compared with other vasodilators papaverin and diltiazem. Ring segments of IMA were studied in organ baths for measurement of isometric tension. After the tissues has reached their baseline tension, precontraction was induced by 100 mm KCl and cumulative concentration-relaxation was measured by the application of iloprost (10(-9)-10(-6) m), papaverine (10(-5)-10(-4) m), diltiazem (10(-9)-10(-4) m) or ethanol; a solvent for iloprost; alone. The maximal relaxation of IMA segments to iloprost was 13.5 +/- 2.2%. Iloprost caused significantly limited relaxation when compared with papaverin (106.0 +/- 2.9%) and diltiazem (93.6 +/- 2.5%) (P < 0.001). Papaverin produced the greatest maximal relaxation to KCl-induced contraction of IMA. The potency of iloprost (-log EC(50) = 6.59 +/- 0.19) was significantly higher than those of papaverine (-log EC(50) = 4.21 +/- 0.11) and diltiazem (-log EC(50) = 5.63 +/- 0.06) (P < 0.001). In addition, -log EC(50) of diltiazem was significantly greater than papaverin (P < 0.001). Iloprost appears to be more potent than those of papaverine and diltiazem but it was inefficient in maximal inhibition on KCl-induced contraction. Iloprost may have little benefit in KCl-related vasoconstriction on human IMA segments.
More Related Videos
Related Concept Videos
01:17Autoregulation of Blood Flow
Chemical Signaling in Autoregulation
Chemical signaling operates at the precapillary sphincter level, inciting either contraction or relaxation.
01:23Treatment for Pulmonary Arterial Hypertension: Prostacyclin Receptor Agonists
These agonists bind to the IPR receptor situated on the plasma membrane of the pulmonary artery smooth muscle cells. This binding triggers a cascade of reactions known as the GS-AC-cAMP-PKA pathway. This pathway results in the relaxation of smooth muscle...