vasoregulation

Vasoregulation is the physiological process by which the tone of blood vessel walls is adjusted to regulate vascular resistance and blood flow. It involves arteriolar smooth muscle, endothelial signals, neural inputs, and circulating hormones, coordinating to maintain perfusion of tissues and overall blood pressure within a healthy range.

Key mechanisms include endothelial control of vascular tone through substances such as nitric oxide, prostacyclin, and endothelin-1; smooth muscle calcium signaling and ion channel activity; and intrinsic myogenic responses to changes in pressure. Local metabolic factors like adenosine, carbon dioxide, hydrogen ion concentration, and oxygen levels also influence dilation or constriction in a tissue-specific manner.

Regulation operates at multiple levels. The autonomic nervous system modulates tone through sympathetic vasoconstriction and, in some beds, vasodilation via beta-adrenergic signaling. Circulating hormones such as angiotensin II, vasopressin, epinephrine, and atrial natriuretic peptide further adjust vascular resistance. Local autoregulation and reflexes, including baroreceptors and chemoreceptors, help stabilize mean arterial pressure and ensure adequate tissue perfusion despite fluctuations in systemic conditions.

Physiological roles include controlling mean arterial pressure, directing blood flow to organs and tissues based on demand, and contributing to thermoregulation through skin perfusion. Dysregulation of vasoregulation can contribute to conditions such as hypertension, hypotension, shock, and endothelial dysfunction. Therapeutic strategies often target vasoregulation, using vasodilators or vasoconstrictors to restore appropriate vascular tone and perfusion.