autoregulate

Autoregulate, or autoregulation, refers to the ability of a system to regulate its own state without external input. In biology and medicine, autoregulation describes intrinsic mechanisms that maintain stable conditions within an organ or tissue despite changes in perfusion pressure or the external environment, thereby protecting cells from injury.

A prominent example is cerebral autoregulation, the brain’s capacity to keep cerebral blood flow roughly constant across a range of mean arterial pressures. This stability arises from a combination of myogenic responses of cerebral arterioles, metabolic signals such as carbon dioxide and hydrogen ions, and endothelium-derived factors like nitric oxide.

The kidney also autoregulates glomerular filtration rate, adjusting the tone of the afferent arteriole in response to blood pressure changes to preserve filtration and electrolyte balance. Similar autoregulatory mechanisms operate in other vascular beds and organs, including the heart and liver, with pathways that commonly involve smooth muscle tone and local metabolic signaling.

Clinical relevance: impaired autoregulation can increase tissue vulnerability during episodes of hypotension or hypertension and influence outcomes after brain injury, stroke, or ischemia. Assessment and management focus on maintaining perfusion within the organ’s autoregulatory range, using monitoring and interventions to avoid crossing that range.

Beyond physiology, autoregulation is also used in engineering and control theory to describe systems that adjust their parameters automatically to maintain performance. The term combines auto- (self) with regulate (to govern or control).