ISSN:
1432-2013
Keywords:
Mammals
;
Systemic Arterial Pressure
;
Equifinality
;
Regulation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The reversible equifinal state in the circulatory system was obtained in pentobarbital anesthetized dogs, cats and rats, by means of the intravenous injection of hexamethonium, with production of an autonomic blockade and a reduction of the systemic arterial pressure to about 50% of the initial value. Equifinality was also obtained in dogs after the cervical injection of lidocaine into the spinal canal; the functional exclusion of ponto-medullary cardiovascular centers also produced a decrease in arterial pressure. The reactivity of these dogs was studied during the occlusion (step function) of either the abdominal aorta or of both common carotid arteries and compared to the pressure responses during control periods. After the autonomic blockade with hexamethonium the normal increase in blood pressure observed after bilateral carotic occlusion was not present and the relative increase in blood pressure during aortic occlusion was not followed afterwards by the reflex decrease observed in control animals. The main differences between normal blood pressure regulation in the circulatory system under normal, or equifinal conditions are analyzed using hydraulic models, block diagrams and signal flow diagrams. From the present study it may be concluded that the mammalian circulatory system is able to accomplish the blood transport in the resting state, either with normal controls or in the equifinal condition, despite the fact that in the latter no autonomic regulations are present.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00589223
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