Nitric oxide/cGMP signalling mediates the cardioprotective action of adrenomedullin in reperfused myocardium.

We demonstrated previously that adrenomedullin (AM), when given during early reperfusion, limited infarct size in rat heart. The present study was undertaken to provide direct evidence of the NO-dependency of AM's cardioprotective action by assessing NO biosynthesis and involvement of the soluble guanylyl cyclase (sGC) pathway. Perfused hearts from male CD-1 mice were subjected to 30-min left coronary occlusion and 60-min reperfusion.

Cardioprotective actions of peptide hormones in myocardial ischemia.

The myocardium represents a major source of several families of peptide hormones under normal physiological conditions and the plasma concentrations of many of these "cardiac peptides" (or related pro-peptide fragments) are substantially augmented in many cardiac disease states. In addition to well-characterised endocrine functions of several of the cardiac peptides, pleiotropic functions within the myocardium and the coronary vasculature represent a significant aspect of their actions in health and disease. Here, we focus specifically on the cardioprotective roles of four major peptide families in myocardial ischemia and reperfusion: adrenomedullin, kinins, natriuretic peptides and the urocortins.

Rho kinase activation plays a major role as a mediator of irreversible injury in reperfused myocardium.

Intracellular signal transduction events in reperfusion following ischemia influence myocardial infarct development. Here we investigate the role of Rho kinase (ROCK) activation as a specific injury signal during reperfusion via attenuation of the reperfusion injury salvage kinase (RISK) pathway phosphatidylinositol 3-kinase (PI3K)/Akt/endothelial nitric oxide (NO) synthase (eNOS). Rat isolated hearts underwent 35 min of left coronary artery occlusion and 120 min of reperfusion.

A critical cytoprotective role of endogenous adrenomedullin in acute myocardial infarction.

Exogenous administration or transfection of adrenomedullin (AM) affords protection against ischaemia-reperfusion injury. Here we have examined the role of endogenous AM in regulating the development of myocardial infarction. Wild type (WT) and AM(+/-) mice underwent 30 min regional myocardial ischaemia and 120 min reperfusion.

Observing three-dimensional human microvascular and myogenic architecture using conventional fluorescence microscopy.

Microangiography and vascular casting have previously been used to demonstrate the three-dimensional architecture of human uterine microvasculature. However, a limitation of these perfusion-dependent techniques is the difficulty in identifying surrounding tissue components. We have previously shown that it is possible to visualise microvascular networks on the cut surfaces of fresh tissue specimens by diffusive labelling of vascular endothelium with fluorescently conjugated UEA-1 lectin.

Visualisation of morphological changes in living intact human microvessels using confocal microscopy.

Conventional techniques to visualise microvascular structure often involve fixed tissue slices that provide two-dimensional images. A previous study using diffusive labelling of fresh, dissected tissue samples with fluorescently-tagged endothelial markers demonstrated the possibility of examining the three-dimensional architecture of the microvasculature using confocal microscopy. The present study extends the use of this quick and simple method of diffusive labelling to examine the possibility of repeatedly measuring changes in the morphology of intact microvessel in response to pharmacological stimuli.

Adrenomedullin: regulator of systemic and cardiac homeostasis in acute myocardial infarction.

During and following acute myocardial infarction, a variety of endogenous mediators are elevated, one of which is adrenomedullin (AM). AM is a multifunctional peptide that has been identified as having a putative beneficial role following an ischemic insult at both systemic and local levels. Classically described as a potent vasodilator, natriuretic, and diuretic agent, experimental infarct models also demonstrate AM to exhibit antiproliferative and antiapoptotic functions in the myocardium, counterregulating the effects of mediators such as angiotensin-II and endothelin-1.

Visualization of live endothelial cells ex vivo and in vitro.

The present study describes quick and effective methods that allow visualization of the vascular endothelium in living networks within dissected pieces of human tissue or in primary cultures containing heterogeneous cell populations. Fresh human uterine and subcutaneous gluteal fat tissues were directly labelled using fluorescently conjugated Ulex Europaeus Agglutinin I (UEA-1) to visualize the three-dimensional nature of the vascular network. Using conventional epi-illuminescence microscopy, the convoluted architecture demonstrating branch points within capillaries, between capillaries and larger vessels, were clearly observed in uterine and subcutaneous gluteal fat samples.