RESUMO
In cats, the rheogram of a portion of the vascular tract was recorded during changes of the eye pressure due to brief increase or decrease of the central arterial pressue. Comparison of the recorded changes with the oscillations of electrical conductivity suggest that the latter reflect primarily the changes of the blood linear speed during the time of one pulse cycle (at frequencies over 30 kHz). Slow changes of the electrical conductivity as recorded during electroplethysmography of the vascular tract, reflect primarily the changes of blood volume in the eye tunics.
Assuntos
Olho/irrigação sanguínea , Animais , Pressão Sanguínea , Gatos , Hemorragia/fisiopatologia , Pressão Intraocular , Pletismografia de Impedância , Pulso Arterial , ReologiaRESUMO
Changes of the intraocular pressure in alterations of the central arterial pressure are an accepted fact. Disbalance of the above changes occurring at that is considered to be a display of active regulatory mechanisms. In this study, comparison of the pulse waves and short--term changes of arterial pressure with oscillations of the intraocular pressure occurring at that, has been made. Analysis of all the changes was made with the aid of a mathematical model. Amplitude--phasic characteristics of the eye membrane were studied for ascertaining of effect of different factors on the amplitude and form of the intraocular pressure pulse waves. In experimental conditions, the differences in dynamics of the level and in form of the pulse oscillations between the central arterial and the intraocular pressures were shown to be due not to functioning of active regulatory mechanisms but to the elastic--viscous features of the eye membrane.
Assuntos
Pressão Sanguínea , Pressão Intraocular , Animais , Gatos , Hemorragia/fisiopatologia , Matemática , Modelos Biológicos , Pulso ArterialRESUMO
A mathematical model for estimation of regulatory abilities of pial and intracerebral arteries was used for studying the pressure - radius relationships for arteries of various calibres in passive and active states. In passive state the arteries were found to be characterized by high elasticity and low tensile force. The radius of the artery depends mainly on the smooth muscle contractile force. The data obtained suggest that the wall structure of small pial and intracerebral arteries well correspond to their function: the control of the adequate and rapid cerebral blood flow.