Cutaneous vasoconstriction in conscious rabbits during alerting responses detected by hippocampal theta-rhythm.
We determined whether alerting stimuli cause cutaneous vasoconstriction in conscious rabbits. We compared ear blood flow with renal, mesenteric, and femoral flows at rest and in response to nonnoxious alerting stimuli, which induced theta-rhythm (4-9 Hz) in the simultaneously recorded hippocampal electroencephalogram (EEG). theta-Inducing stimuli (e.g., whistles and fur touches) reduced ear flow by 95 +/- 6%, commencing 1-2 s after the EEG change and lasting 45 s. Renal flow did not significantly change with alerting stimuli, mesenteric and femoral flows slightly decreased, arterial pressure transiently rose (+10 +/- 3 mmHg), and heart rate fell (+43 +/- 9 beats/min). At rest, the coefficient of variation for ear flow (62 +/- 6%) was greater than for other flows (P < 0.01). Phentolamine (1 mg/kg iv) reduced this coefficient to 29 +/- 4% (P < 0.01). Our study demonstrates that alerting responses in conscious rabbits are associated with selective cutaneous vasoconstriction, without increase in flow to skeletal muscle.
Yu
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YH
Department of Medicine, Flinders University, Bedford Park, Australia. mnyy@cc.flinders.edu.au
Blessing
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D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001143:Arousal / Q000502:physiology*; D001158:Arteries / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D004423:Ear / Q000098:blood supply; D004569:Electroencephalography; D005263:Femoral Artery / Q000502:physiology; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D010646:Phentolamine / Q000494:pharmacology; D011817:Rabbits; D012039:Regional Blood Flow / Q000187:drug effects; D012079:Renal Circulation; D012867:Skin / Q000098:blood supply*; D013152:Splanchnic Circulation; D013826:Theta Rhythm; D013997:Time Factors; D014661:Vasoconstriction
D000317:Adrenergic alpha-Antagonists; D010646:Phentolamine