title: Arteriolar vasomotion and arterial pressure reduction in rabbit tenuissimus muscle.
abstract: Spontaneous arteriolar vasomotion and its relation to arterial pressure reduction was studied in the rabbit tenuissimus muscle using intravital microscopy. Vasomotion was observed in all transverse arterioles and their first-order side branches. Vasomotion frequency ranged from 5 to 32 cycles per minute (median: 25 cpm). The relative vasomotion amplitude in transverse arterioles varied from 0.06 to 0.44 (median: 0.22). Vasomotion was generally of the on-off type in first-order side branches. A gradual reduction in arterial pressure as achieved by aortic occlusion resulted in an abrupt disappearance of vasomotion. Vasomotion disappeared between 19 and 59 mm Hg (median: 30.4 mm Hg). No differences were found between the pressures at which vasomotion ceased in transverse arterioles and first-order side branches. With a further reduction of arterial pressure transverse arterioles attained a maximal diameter of 98-265% (median: 119%) of the maximal diameter during vasomotion. After release of occlusion vasomotion reappeared much earlier in the first-order side branches than in their feeding transverse arterioles. It is concluded that although vasomotion influences capillary perfusion, it does not play a major role in the adaptation of vascular resistance following a reduction in arterial pressure.
mesh_terms: D000818:Animals; D001158:Arteries / Q000502:physiology*; D001160:Arterioles / Q000502:physiology*; D001794:Blood Pressure; D005260:Female; D006940:Hyperemia / Q000503:physiopathology; D008297:Male; D009132:Muscles / Q000098:blood supply*; D011817:Rabbits; D014655:Vascular Resistance; D014661:Vasoconstriction