title: Regional cerebral blood flow in the frontal, parietal and occipital cortices increases independently of systemic arterial pressure during slow walking in conscious rats.
abstract: Regional cerebral blood flow (rCBF) in the frontal, parietal and occipital cortices was measured using laser Doppler flowmetry during walking in conscious rats at moderate speed on a treadmill (4 cm/s) for a 30 s period. During walking rCBF increased in all these three cortices. The rCBF in the parietal cortex started to increase within a few seconds after the start of walking, and continued to increase 42 +/- 16% (mean +/- S.D.) until the end of walking. Within 90 s after walking had ceased, the increased rCBF returned to pre-walking basal levels. The rCBF responses in the frontal and occipital cortices were identical to that in the parietal cortex. Mean arterial pressure (MAP) in a caudal artery of the tail during walking was increased by about 10%. Injection of atropine (5 mg/kg, i.p.), a muscarinic cholinergic receptor antagonist that permeates the blood brain barrier (BBB), reduced the walking-induced increase in cortical rCBF, as determined by measurement of parietal rCBF, from 42 +/- 12% to 28 +/- 15%. However, injection of methylatropine (5 mg/kg, i.p.), a muscarinic cholinergic receptor antagonist that does not permeate the BBB, did not affect the response of rCBF. Neither drug affected the walking-induced response of MAP. Injection of mecamylamine (20 mg/kg, s.c.), a nicotinic cholinergic receptor antagonist that permeates the BBB, reduced the walking-induced increase in cortical rCBF from 47 +/- 12% to 30 +/- 12%. Injection of hexamethonium (20 mg/kg, s.c.), a nicotinic cholinergic receptor antagonist that does not permeate the BBB, did not affect the responses of rCBF.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Autonomic Nervous System, Tokyo Metropolitan Institute of Gerontology, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Kimura
authors.forename: K
authors.initials: K
authors.lastname: Okada
authors.forename: A
authors.initials: A
authors.lastname: Sato
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D001794:Blood Pressure; D002560:Cerebrovascular Circulation; D005625:Frontal Lobe / Q000098:blood supply*; D017078:Laser-Doppler Flowmetry; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D018727:Muscarinic Antagonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D009778:Occipital Lobe / Q000098:blood supply*; D010296:Parietal Lobe / Q000098:blood supply*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D018727:Muscarinic Antagonists; D018733:Nicotinic Antagonists