Related Experiment Videos
Activated human polymorphonuclear leukocytes elicit endothelium-dependent contraction in isolated pig coronary
T Murohara1, K Kugiyama, S Sugiyama
1Division of Cardiology, Kumamoto University School of Medicine, Japan.
Abstract:
Interaction between activated human polymorphonuclear leukocytes (PMNL) and endothelial regulation of isolated pig coronary artery tone was examined. PMNL were isolated from venous blood of healthy human volunteers. Pig coronary artery rings were incubated in an organ chamber, and isometric tension changes induced by opsonized zymosan (1 mg/ml)-activated PMNL were examined. Activated PMNL elicited dose-dependent contraction (maximum value 45.9 +/- 4.1% of precontraction, mean +/- SEM] in prostaglandin F2 alpha (PGF2 alpha)-precontracted rings. The contraction was markedly attenuated by superoxide dismutase (SOD 100 U/ml) to 9.9 +/- 2.4% (p < 0.001), but not by catalase (1,000 U/ml). After inhibition of basal production of endothelium-derived relaxing factor (EDRF) (nitric oxide, NO) by endothelial removal or by treatment of an inhibitor of NO synthase, NG-monomethyl-L-arginine (L-NMMA), PMNL also failed to induce the contraction. A 5-lipoxygenase inhibitor (AA-861) and a cyclooxygenase inhibitor (indomethacin) did not alter the contraction to activated PMNL significantly. Time course of oxygen free radical release from PMNL measured by luminol-dependent chemiluminescence was closely synchronized with that of the endothelium-dependent contraction elicited by PMNL. In each preparation of PMNL, the maximum luminescence count and the maximum contraction induced by activated PMNL showed significant positive correlation quantitatively (r = 0.958, p < 0.001). Activated human PMNL elicited endothelium-dependent contraction in isolated pig coronary arteries. The contraction may be mediated through inactivation of basal production of EDRF (NO) by superoxide anions released from PMNL.
Insights
Activated human polymorphonuclear leukocytes (PMNL) cause contraction in pig coronary arteries. This effect is mediated by superoxide anions from PMNL, which inactivate nitric oxide (NO) produced by the endothelium.
Area of Science:
- Cardiovascular Physiology
- Immunology
- Endothelial Biology
Background:
- Polymorphonuclear leukocytes (PMNL) play a role in inflammation and vascular responses.
- Endothelial cells regulate vascular tone through various signaling pathways, including nitric oxide (NO).
Purpose of the Study:
- To investigate the interaction between activated human PMNL and endothelial regulation of pig coronary artery tone.
- To determine the mechanisms underlying PMNL-induced vascular contractions.
Main Methods:
- Isometric tension measurements in isolated pig coronary artery rings.
- Incubation with opsonized zymosan-activated human PMNL.
- Assessment of the effects of superoxide dismutase (SOD), catalase, NG-monomethyl-L-arginine (L-NMMA), AA-861, and indomethacin.
- Measurement of PMNL oxygen free radical release via luminol-dependent chemiluminescence.
Main Results:
- Activated PMNL induced a dose-dependent contraction in prostaglandin F2 alpha-precontracted coronary artery rings.
- The contraction was significantly attenuated by SOD but not by catalase.
- Inhibition of nitric oxide synthase (NOS) or endothelial removal abolished the PMNL-induced contraction.
- PMNL-induced contraction correlated positively with oxygen free radical release.
Conclusions:
- Activated human PMNL elicit endothelium-dependent contractions in isolated pig coronary arteries.
- The contraction is mediated by superoxide anions released from PMNL, which inactivate endothelium-derived relaxing factor (nitric oxide).