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Showing papers by "Joseph L. Izzo published in 1990"


Journal ArticleDOI
TL;DR: In the northern US, wintertime vasoconstriction is related to increased sympathetic nervous activity and decreased cardiac output, and when these reciprocal changes are proportional, blood pressure remains constant.

83 citations


Journal ArticleDOI
TL;DR: It can be roughly estimated that changes in stroke volume account for as much as 60% of the postural variation in plasma NE in hypertensives, whereas only 15% of this variation is caused by changes in carotid sinus pressure.
Abstract: The contributions of the carotid sinus and cardiopulmonary baroreflexes to the interindividual variation in sympathetic nervous system activation caused by postural adaptation were indirectly assessed in 68 mild hypertensive subjects. Supine and upright plasma norepinephrine (NE), blood pressure (cuff) and cardiac output (acetylene rebreathing) were measured. Mean arterial pressure (MAP), carotid sinus pressure, stroke volume and systemic vascular resistance were calculated. Stroke volume was assumed to be proportional to the degree of stretch of cardiac mechanoreceptors, carotid sinus MAP was assumed to be proportional to carotid sinus stretch and plasma NE to reflect sympathetic nervous activity. Plasma NE correlated inversely with stroke volume (r = −0.62, p −14 ) and estimated carotid sinus MAP (r = −0.33, p −10 ). Holding systemic vascular resistance constant by partial regression, the inverse relation between plasma NE and stroke volume remained (partial r = −0.36, p

9 citations