Cholinergic control of the cerebral vasculature in humans.
Despite growing evidence of autonomic nervous system involvement in the regulation of cerebral blood flow, the specific contribution of cholinergic vasodilatation to cerebral autoregulation remains unknown. We examined cerebral and forearm blood flow responses to augmented arterial pressure oscillations with and without cholinergic blockade. Oscillatory lower body negative pressure was applied at six frequencies from 0.03 to 0.08 Hz in nine healthy subjects with and without cholinergic blockade via glycopyrrolate. Cholinergic blockade increased cross-spectral coherence between arterial pressure and cerebral flow at all frequencies except 0.03 Hz and increased the transfer function gain at frequencies above 0.05 Hz. In contrast, gain between pressure and forearm flow increased only at frequencies below 0.06 Hz. These data demonstrate that the cholinergic system plays an active and unique role in cerebral autoregulation. The frequency region and magnitude of effect is very similar to what has been seen with sympathetic blockade, indicating a possible balance between the two reflexes to most effectively respond to rising and falling pressure. These findings might have implications for the role of dysfunction in autonomic control of the vasculature in cerebrovascular disease states.
Cardiovascular Research Laboratory, Spaulding Hospital Cambridge, Cambridge, MA 02138, USA.
J W
JW
Hamner
Can Ozan
CO
Tan
Yu-Chieh
YC
Tzeng
J Andrew
JA
Taylor
D000328:Adult; D062186:Arterial Pressure; D001783:Blood Flow Velocity / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D002799:Cholinergic Fibers / Q000187:drug effects*; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006024:Glycopyrrolate / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006706:Homeostasis; D006801:Humans; D008150:Lower Body Negative Pressure; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000294:innervation; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D012039:Regional Blood Flow / Q000187:drug effects; D013997:Time Factors; D017585:Ultrasonography, Doppler, Transcranial; D055815:Young Adult
D018727:Muscarinic Antagonists; D006024:Glycopyrrolate