Vasodilation theory

To explain the complex mechanisms of ascites formation, four hypotheses have been developed in the light of experimental and clinical findings (i.) underfill theory, (2.) overflow theory, (5.) lymph imbalance theory, and 4.) vasodilation theory, (s. fig. 16.6)... 

Despite their successful use for at least 20 years, the mechanisms by which they lower the blood pressure remain uncertain. Theories to explain the antihypertensive effectiveness of the diuretic agents have included a) alteration of sodium and water content on arterial smooth muscle, b) the induction of a decreased vascular response to catecholamines, c) a decrease in blood volume and total extracellular fluid volume, and d) a direct vasodilator action independent from the diuretic effect(12). 

Several lines of investigation have provided evidence to support the theory that CGRP plays a role in migraine. CGRP is the most abundant primary afferent peptide in trigeminal sensory nerves. Since CGRP is one of the most potent vasodilators known and the CGRP receptor is... 

Another postulated mechanism is an altered function of the central nervous and respiratory systems through an amplification of a nonspecific inflammatory response to low-level irritants (neurogenic inflammation hypothesis). This suggests that MCS may be initiated by the interaction of chemical irritants with sensory nerves or C-fiber neurons, a nonspecific response pathway. It is proposed that inhaled chemicals stimulate irritation receptors which activate sensory nerves to release mediators producing vasodilation, edema, and other manifestations of inflammation, leading to neurogenic inflammation. There is some evidence in animals for this theory. 

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