Interaction between nitric oxide synthase inhibitor induced oscillations and the activation flow coupling response

• Published in: Brain research 2010-01, Vol.1309, p.19-28
• Main Authors: Ances, Beau M, Greenberg, Joel H, Detre, John A
• Format: Article
• Language: English
• Subjects: Afferent Pathways - drug effects; Afferent Pathways - physiology; and Cerebral blood flow; Animals; Biological and medical sciences; Biological Clocks - drug effects; Biological Clocks - physiology; Cerebral Arteries - drug effects; Cerebral Arteries - physiology; Cerebral circulation. Blood-brain barrier. Choroid plexus. Cerebrospinal fluid. Circumventricular organ. Meninges; Cerebrovascular Circulation - drug effects; Cerebrovascular Circulation - physiology; Electric Stimulation; Enzyme Inhibitors - pharmacology; Fundamental and applied biological sciences. Psychology; Laser Doppler flowmetry; Male; Neurology; Nitric oxide; Nitric Oxide - metabolism; Nitric Oxide Synthase Type I - antagonists & inhibitors; Nitric Oxide Synthase Type I - metabolism; Nitroarginine - pharmacology; Oscillation; Rats; Rats, Sprague-Dawley; Somatosensory Cortex - blood supply; Somatosensory Cortex - drug effects; Somatosensory Cortex - physiology; Time Factors; Vasodilation - drug effects; Vasodilation - physiology; Vasodilator Agents - metabolism; Vasodilator Agents - pharmacology; Vasomotor System - drug effects; Vasomotor System - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2009.09.119

Abstract The role of nitric oxide (NO) in the activation-flow coupling (AFC) response to periodic electrical forepaw stimulation was investigated using signal averaged laser Doppler (LD) flowmetry. LD measures of calculated cerebral blood flow (CBF) were obtained both prior and after intra-peritoneal administration of the non-selective nitric oxide synthase (NOS) inhibitor, NG -nitro- l -arginine ( l -NNA) (40 mg/kg). Characteristic baseline low frequency vasomotion oscillations (0.17 Hz) were observed after l -NNA administration. These LDCBF oscillations were synchronous within but not between hemispheres. l -NNA reduced the magnitude of the AFC response ( p < 0.05) for longer stimuli (1 min) with longer inter-stimulus intervals (2 min). In contrast, the magnitude of the AFC response for short duration stimuli (4 s) with short inter-stimulus intervals (20 s) was augmented ( p < 0.05) after l -NNA. An interaction occurred between l -NNA induced vasomotion oscillations and the AFC response with the greatest increase occurring at the stimulus harmonic closest to the oscillatory frequency. Nitric oxide may therefore modulate the effects of other vasodilators involved in vasomotion oscillations and the AFC response.