Basal tone of vascular smooth muscles

Independent of the nervous system
* Unlike skeletal muscle tones

Contributing factors

(for basal tone of vascular smooth muscles)

Mostly unknown

But probably involve one or more of the following:

• Myogenic activity in response to stretch by blood pressure
• High O2 tension of arterial blood
• Presence of Ca2+ ions
• Unknown factors in plasma

Reactive hyperemia

= Increased blood flow immediately after release of occlusion, exceeding the flow before occlusion

60 second occlusion
* Peak blood flow about 70% greater
* Returns to normal in 110 seconds

Peak flow and duration of the reactive hyperemia are proportional to the duration of the occlusion