Mikrovaskuläre

Mikrovaskuläre (microvasculature) refers to the smallest components of the circulatory system, including arterioles, capillaries, venules, and their surrounding supporting cells. The microvasculature forms the primary site of exchange between blood and tissues, enabling delivery of oxygen and nutrients and the removal of carbon dioxide and waste. Its networks are locally organized to meet tissue-specific metabolic needs and can adapt rapidly to changes in demand.

The walls of microvessels are specialized. Endothelial cells line the lumen and regulate permeability, filtration, and vascular tone. Surrounding pericytes and, in some vessels, smooth muscle cells provide structural support and contractility. The basement membrane and glycocalyx contribute to barrier properties and mechanotransduction. Capillaries vary in density and structure, ranging from continuous to fenestrated forms, reflecting different physiological roles.

Regulation of microvascular function involves both local and systemic signals. Endothelial cells release vasoactive substances such as nitric oxide and endothelin, modulated by shear stress, hypoxia, and metabolic factors. Blood flow is adjusted through arteriolar tone and autoregulatory mechanisms to maintain tissue perfusion. Transport across microvessels occurs mainly by diffusion and transcytosis, with lymphatic vessels helping maintain interstitial fluid balance.

Clinical relevance abounds. Microvascular dysfunction is a key feature in many diseases, notably diabetes mellitus, where microvascular complications include retinopathy, nephropathy, and distal neuropathy. Hypertension, inflammatory conditions, and ischemic diseases also involve microvascular remodeling and impaired perfusion. Assessment approaches include capillaroscopy, skin perfusion or laser Doppler techniques, and imaging methods to evaluate microvascular perfusion and permeability. Understanding mikrovasculature supports diagnosis, prognosis, and therapeutic strategies targeting endothelial function and vascular health.