Experiments were performed on 45 cats. One group of animals was operated upon utilizing ether anesthesia which was discontinued after brain stem transsection. During the following experimental procedure the animals were immobilized with Flaxedil and artificially respired. Another series of experiments was carried out under Pentobarbital Sodium anesthesia (Nembutal).
The brain stem was successively transsected according to the Horsley-Clarke coordinates A 2 (section I), P 2 (section II), and P 6 (section III). These sections are located rostrally to the rhombencephalic vasomotor center. Blood pressure elevations were produced by intravenous injection of adrenaline.
The height of blood pressure did not change if mesencephalic structures were removed by the three sections. The duration of the adrenaline-induced rise in blood pressure was significantly prolonged after successive removal of the mesencephalic brain stem structures. This effect was abolished under Nembutal anesthesia. In this case the duration of the adrenaline-induced rise in blood pressure was found to be identical with the response to transsection in position III in unanesthetized cats.
The increased duration of the adrenaline-induced blood pressure elevation after successive transsection of mesencephalic structures can still be observed after denervation of the carotid sinus bilaterally. Even though the differences observed were less pronounced, they remained statistically significant.
Comparable results were obtained when both carotid sinus and depressor nerves were interrupted.
If all buffer nerves including both vagi were cut, the duration of the rise in blood pressure continued to increase with each step of the mesencephalic transsection.
In another series of experiments the rhombencephalic vasomotor center was isolated by deafferentiation from all buffer nerves and separated from higher brain stem structures by section III. The duration of an adrenaline-induced rise in blood pressure under these circumstances was not significantly longer than that observed after a subsequently performed spinal section at C1.
In conclusion it can be said that mesencephalic brain stem structures are involved in the phasic regulation of blood pressure.
The results of the experiments suggest that the baroreceptor reflex arc sends collaterals to the mesencephalon. Since a less pronounced mesencephalic influence on blood pressure regulation can still be observed after deafferentiation from all buffer nerves, the conclusion is reached that additional pressosensitive structures within the mesencephalon participate in the regulation of blood pressure. Application of barbiturates induces complete blockage of the described mesencephalic influence on blood pressure regulation.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Alexander, R. S.: Tonic and reflex function of medullary sympathetic cardiovascular centers. J. Neurophysiol. 9, 205–217 (1946).
Bard, Ph.: Anatomical organization of the central nervous system in relation to control of the heart and blood vessels. Physiol. Rev. 40, Suppl. 4, 3–26 (1960).
Baust, W.: Zentralnervöse Mechanismen emotionaler Kreislaufbelastungen. Verh. dtsch. Ges. Kreisl.-Forsch. 32, 37–46 (1966).
——, and H. Niemczyk: Studies on the adrenaline-sensitive component of the mesencephalic reticular formation. J. Neurophysiol. 26, 692–704 (1963).
Christian, P.: Die funktionelle Bedeutung der Hirnrinde für die Kreislaufregulation. Arch. Kreisl.-Forsch. 21, 174–188 (1954).
Delgado, J. M. R.: Circulatory effects of cortical stimulation. Physiol. Rev. 40, Suppl. 4, 146–171 (1960).
Gutman, J., U. Leibowitz, and F. Bergmann: Effect of brain stem transsection on blood pressure responses to medullary stimulation. Arch. int. Physiol. 70, 671–681 (1962).
Hess, W. R.: Das Zwischenhirn. Basel: Schwabe 1949.
Hilton, S. M.: Inhibition of baroceptor reflexes on hypothalamic stimulation. J. Physiol. (Lond.) 165, 56P-57P (1963).
Kaada, B. R.: Somato-motor, autonomic and electrocorticographic responses to electrical stimulation of rhinencephalic and other structures in primates, cat and dog. Acta physiol. scand. 24, Suppl. 83 (1951).
Katz, R. L., C. Y. Chai, N. Kahn, S. H. Ngai, N. N. Share, and S. C. Wang: Brain stem mechanisms subserving baroreceptor reflexes. Science 145, 1459 to 1460 (1964).
Keller, A. D.: Ablation and stimulation of the hypothalamus: Circulatory effects. Physiol. Rev. 40, Suppl. 4, 116–135 (1960).
Lindgren, P.: The mesencephalon and the vasomotor system. Acta physiol. scand. 35, Suppl. 121 (1955).
MacLean, P. D., D. W. Ploog, and B. W. Robinson: Circulatory effects of limbic stimulation, with special reference to the male genital organ. Physiol. Rev. 40, Suppl. 4, 105–112 (1960).
Monnier, M.: Physiologie des vegetativen Nervensystems in: Physiologie und Pathophysiologie des vegetativen Nervensystems, Band I: Physiologie, hrsg. von Monnier, M. S., S. 52–359. Stuttgart: Hippokrates 1963.
Oberholzer, R. J. H.: Circulatory centers in medulla and midbrain. Physiol. Rev. 40, Suppl. 4, 179–195 (1960).
Peiss, C. N.: Cardiovascular responses to electrical stimulation of the brain stem. J. Physiol. (Lond.) 141, 500–509 (1958).
Poeck, K.: Die klinische Bedeutung des limbischen Systems. Nervenarzt 35, 152–161 (1964).
Rushmer, R. F.: Cardiovascular dynamics. London: W. B. Saunders 1961.
Uvnäs, B.: Central cardiovascular control, in: Handbook of Physiology. Sect. 1: Neurophysiology, Vol. II, pp. 1131–1162, hrsg. von Field, J., H. W. Magoun, and V. E. Hall. Baltimore: Williams and Wilkens 1960.
Weidinger, H.: Das Vasomotorenzentrum in der Medulla oblongata. Versuche zur Bestimmung seiner Lage und Funktion. Habilitationsschrift, Heidelberg 1966.
Herrn Prof. Dr. H. Schaefer zum 60. Geburtstag.
Mit Unterstützung der Deutschen Forschungsgemeinschaft.
About this article
Cite this article
Baust, W., Niemczyk, H. Der Einfluß mesencephaler Strukturen auf die phasische Blutdruckregulation. Pflügers Arch. 301, 31–42 (1968). https://doi.org/10.1007/BF00412416
- Blood Pressure Regulation
- Mesencephalic Reticular Formation