Pathogenesis of hypertension

MyD88: At the heart of inflammatory signaling and cardiovascular disease

Cardiovascular disease is a leading cause of death worldwide and is associated with systemic inflammation. In depth study of the cell-specific signaling mechanisms mediating the inflammatory response is vital to improving anti-inflammatory therapies that reduce mortality and morbidity. Cellular damage in the cardiovascular system results in the release of damage associated molecular patterns (DAMPs), also known as "alarmins," which activate myeloid cells through the adaptor protein myeloid differentiation primary response 88 (MyD88). MyD88 is broadly expressed in most cell types of the immune and cardiovascular systems, and its role often differs in a cardiovascular disease context and cell specific manner. Herein we review what is known about MyD88 in the setting of a variety of cardiovascular diseases, discussing cell specific functions and the relative contributions of MyD88-dependent vs. independent alarmin triggered inflammatory signaling. The widespread involvement of these pathways in cardiovascular disease, and their largely unexplored complexity, sets the stage for future in depth mechanistic studies that may place MyD88 in both immune and non-immune cell types as an attractive target for therapeutic intervention in cardiovascular disease.

Regional vasomotor tone in normotensive and hypertensive dogs

A new method for estimating vasomotor tone in a local circulation by means of the asystolic arterial pressure gradient was applied to the renal, femoral, brachial, and mesenteric vascular beds of normal dogs and of dogs made hypertensive by various technics. The splanchnic circulation apparently contributes the greatest proportion of the increase of resistance in anesthetized hypertensive animals. The correlation of vasomotor tone with diastolic pressure was good only in the mesenteric area. Some differences in these four areas were found between renal and neurogenic hypertension.

Systolic Hypertension and Subendocardial Hemorrhages Produced by Electrical Stimulation of the Stellate Ganglion

During prolonged electrical stimulation of the stellate ganglion in the dog, blood pressure, and more specifically systolic pressure, is significantly elevated. The amount of augmentation in pulse pressure is related to the frequency of stimulation, as is the duration of the sustained pressor response. Postmortem examination of the hearts revealed a distinctive pattern of subendocardial hemorrhages distributed along the long axis of the papillary muscles and the trabeculae carneae. They also frequently marked the endocardium at the base of the mitral valve. These lesions appeared in the left ventricle in 29 of 33 animals in which the left stellate ganglion was stimulated at a frequency of three to ten per second. They were found in only five instances in the right ventricles of these animals. The incidence of lesions in the ventricular wall was low during stimulation of the right stellate ganglion, although the mitral valve became involved in about 50 per cent of the animals. The similarity of the lesions to those induced during hemorrhagic hypotension, elevated intracranial pressures, and infusion of large quantities of the catecholamines suggests the possibility of a similar etiology. A satisfactory explanation of the lesion, however, is not yet available.

Studies on the control of hypertension by hyphex. I. Effects on blood pressure

This report is the first of a series on a method for treatment of hypertension by oral hexamethonium chloride and hydrazinophthalazine. When strictly followed blood pressure was maintained at reasonable or normal levels in 80 per cent of 258 cases of severe hypertension. The malignant stage, when present, was reversed. Renal insufficiency and severe cerebral atherosclerosis limit the effectiveness of the method for prolongation of life.

Arterial Hypertension in Dogs

Various methods were devised in attempts to produce chronic hypertension in dogs. The induction of anxiety was unsuccessful. Bilateral renal denervation combined with injections of epinephrine appeared to produce temporary hypertension. Permanent hypertension was induced by unilateral renal ischemia with the other kidney left intact only in dogs of nervous temperament. Certain dogs were extremely resistant to the development of hypertension even when several methods were combined. Neurogenic hypertension induced by section of the moderator nerves is probably a true hypertension. It is obvious that the host factor may be as important as the method employed.