Myogenic tone

Myogenic tone is the intrinsic contractile state of smooth muscle that is independent of neural and hormonal influences. It is a fundamental property of smooth muscle and is important in the regulation of blood flow and blood pressure.

Physiology

The myogenic response is a local process that occurs in response to changes in transmural pressure. When the pressure within a blood vessel increases, the vessel initially expands. This stretch triggers a reflex contraction in the smooth muscle, causing the vessel to constrict and resist further expansion. Conversely, a decrease in transmural pressure causes the vessel to dilate. This response helps to maintain a relatively constant blood flow despite changes in systemic blood pressure.

The exact mechanism of the myogenic response is not fully understood, but it is believed to involve the opening of stretch-activated ion channels in the smooth muscle cell membrane. This leads to an influx of calcium ions, which triggers contraction.

Clinical significance

Abnormalities in myogenic tone can contribute to various cardiovascular diseases, including hypertension and heart failure. For example, increased myogenic tone can lead to excessive vasoconstriction and elevated blood pressure. On the other hand, reduced myogenic tone can result in inadequate blood flow to tissues.

Research

Research into the myogenic response and its role in disease is ongoing. Current areas of focus include the identification of the specific ion channels involved in the response, and the development of drugs that can modulate myogenic tone to treat cardiovascular diseases.

See also

• Smooth muscle
• Blood flow
• Blood pressure
• Cardiovascular diseases

References

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