Electrical Activity Underlying Rhythmic Contraction in Human Pial Arteries

• Published in: Circulation research Vol. 78; no. 1; pp. 148 - 153
• Main Authors: Gokina, Natalia I, Bevan, Rosemary D, Walters, Carrie L
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD American Heart Association, Inc 01.01.1996; Lippincott; Lippincott Williams & Wilkins Ovid Technologies
• Subjects: Adolescent; Adult; Aged; Biological and medical sciences; Calcium Channels - physiology; Cerebral Arteries - physiology; Cerebral circulation. Blood-brain barrier. Choroid plexus. Cerebrospinal fluid. Circumventricular organ. Meninges; Electrophysiology; Fundamental and applied biological sciences. Psychology; Humans; Membrane Potentials; Middle Aged; Muscle Contraction - physiology; Muscle, Smooth, Vascular - physiology; Potassium Channels - physiology; Vertebrates: nervous system and sense organs; Human; Calcium; Electrical activity; Spontaneous; Central nervous system; Electrophysiology; Action potential; Ionic channel; Pial artery; Muscle contraction; Depolarization; Vasomotricity; Blood vessel; Oscillation; Circulatory system; Brain (vertebrata)
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/01.res.78.1.148

Human pial arteries obtained during surgery frequently exhibit spontaneous periodic contractions. Simultaneous measurements of membrane potential and vessel wall force were used to examine whether these contractions are associated with electrical activity of smooth muscle cells (SMCs). A total of 53 segments from 38 patients were studied, and of these, 26 showed spontaneous contractions related to periodic depolarization and generation of action potentials (APs). The resting membrane potential during the silent periods was minus 44.0 plus minus 0.5 mV. APs without ``overshoot'' were observed when spontaneous depolarization reached levels of minus 40 to minus 35 mV. Just over half of the arterial segments failed to exhibit spontaneous activity; however, APs could be generated during K-induced depolarization. The mean SMC resting membrane potential of these vessels was minus 53.5 plus minus 1.5 mV, and this value differed significantly from that of SMCs in spontaneously active arteries. Application of tetrodotoxin did not change the amplitude and duration of APs. Removal of Ca plus from the bathing solution and addition of nifedipine completely inhibited the spontaneous APs and associated contractions. K depolarization failed to induce APs and contraction in the presence of nifedipine. We conclude that periodic spontaneous depolarization and AP generation underlie the periodic spontaneous contractions of human pial arteries. Both the APs and associated contractions are related to the activation of dihydropyridine-sensitive voltage-dependent Ca plus channels. It is suggested that AP generation can be responsible for vasomotion of human pial arteries in vivo.(Circ Res. 1996;78:148-153.)