The control of arterial blood pressure was investigated on three different preparations: “normal” dogs (Group I); headless dogs with normal spinal cords (Group II); headless dogs with the spinal cord destroyed (Group III). On each group an «isohemic» blood volume expansion was performed, by infusing quantitatively equivalent amounts of dextran 70, or autologous blood, previously mixed with the circulating blood. In the dogs of Group II the blood pressure rose, after volume expansion, about half as much as in the dogs of Group III, thus revealing a partial ability of spinal structures to regulate arterial pressure. The gain of the control system of the pressure in Group I was G = — 1.88, while in Group II it was G = — 0.80. The hypothesis is suggested of a possible interaction of an O2-sensitive mechanism with the baroreceptor-bulbar-vasoconstrictor system, at the spinal level.
Referenze Bibliografiche
[1] R. S. ALEXANDER (1945) - The effects of blood flow and anoxia on spinal cardiovascular centers, «Am. J. Physiol.», 143, 698-708.
[2] W. S. BEACHAM e E. R. PERL (1964) - Characteristics of a spinal sympathetic reflex, «J. Physiol.», 173, 431-448.
[3] D. W. BRONX, L. K. FERGUSON, R. MARGARIA e D. Y. SOLANDT (1936) - The activity of the cardiac sympathetic centers, «Am. J. Physiol.», 117, 237-249.
[4] C. M. BROOKS (1933) - Reflex activation of the sympathetic system in the spinal cat, «Am. J. Physiol.», 106, 251-266.
[5] C. M. BROOKS (1935) - The reaction of chronic spinal animals to hemorrhage, «Am. J. Physiol.», 114, 30-39.
[6] A. CEVESE e A. C. GUYTON - «Isohemic» blood volume expansion in normal and headless dogs, «Am. J. Physiol.», in corso di stampa.
[7] A. W. COWLEY, Jr. e A. C. GUYTON (1972) - Quantification of intermediate steps in the renin-angiotensin-vasoconstrictor feedback loop in the dog, «Circ. Res.», 30, 557-566.
[8] F. DE MOLINA e E. R. PERL (1965) - Sympathetic activity and the systemic circulation in the spinal cat, «J. Physiol.», 181, 82-102.
[9] W. A. DOBBS Jr., J. W. PRATHER e A. C. GUYTON (1971) - Relative importance of nervous control of cardiac output and arterial pressure, «Am. J. Cardiol.», 27, 507-512.
[10] G. HOREYSECK e W. JAENING (1974) - Reflex activity in postganglionic fibres within skeletal muscle nerves elicited by somatic stimuli in chronic spinal cats, «Exp. Brain Res.», 21, 155-168.
[11] Y. LAPORTE, P. BESSON e S. BOUISSET (1960) - Action réflexe des différents types de fibres afférentes d'origine musculaire sur la pression sanguine, «Arch. It. Biol.», 98, 206-221.
[12] J. M. LEITNER e E. R. PERL (1964) - Receptors supplied by spinal nerves which respond to cardiovascular changes and adrenaline, «J. Physiol.», 175, 254-274.
[13] S. R. MUKHERJEE (1957) - Effect of bladder distension on arterial blood pressure and renal circulation in acute spinal cats, «J. Physiol.», 138, 300-306.
[14] R. F. PITTS, M. G. LARRABER e D. W. BRONK (1941) - An analysis of hypothalamic cardiovascular control, «Am. J. Physiol.», 134, 359-383.
Con il contributo del Ministero per i Beni e le Attività Culturali