Vasoconstriction is not recognized as a cause of cerebrovascular disease except in the vasospasm seen following subarachnoid hemorrhage and possibly in migraine. However, we found four patients to have transient, fully reversible vasoconstriction and dilatation prominently involving arteries around the circle of Willis. All four patients were evaluated for severe headaches and fluctuating or re...

Pulmonary vascular resistance normally falls or remains unchanged during exercise. Seven children with pulmonary hypertension were exercised during cardiac catheterisation after operative correction of ventricular septal defect (6) and truncus arteriosus (1). Except for the presence of moderate pulmonary hypertension, resting haemodynamics in these seven children were similar to those of normal...

By cutting gill filaments in anesthetized rainbow trout ( Oncorhynchus mykiss), observing the bleeding through a stereomicroscope, and using blockers of various known endogenous filament artery vasoconstrictors, we have here attempted to characterize hemostatic mechanisms in gills. The immediate hemostatic response to a cut in a gill filament artery was a local vasoconstriction, stopping the he...

The isolated kidney of the recipient rat was perfused at a fixed flow rate with blood from a donor by a cross-circulation technique. The renal vasculature responded to the release of arterial occlusion with vasoconstriction, the magnitude of which was increased with increase in the duration of occlusion. ATP, ADP, AMP, adenosine, noradrenaline and 5-HT injected into the renal artery induced a p...

Vasoconstriction is a normal response to a fall in blood volume, but excessive vasoconstriction caused by pressor drugs, while it raises the arterial pressure, is considered to be undesirable because it decreases the already diminished flow through capillaries (1, 2). Pressor drugs are therefore said to be harmful in shock in which there is a diminished blood volume, although many physicians st...

BACKGROUND Postpartum reversible cerebral vasoconstriction syndrome is one of the rare reversible cerebral vasoconstriction syndromes. The clinical presentation is usually characterized by recurrent headache, focal neurological deficit, and reversible cerebral vasoconstriction seen on cerebral angiography. CASE PRESENTATION We report a case of a 35-year-old Yemeni woman who presented with hea...

INTRODUCTION Reversible cerebral vasoconstriction syndrome presents with thunderclap headaches accompanied by mild neurologic deficits and is characterized by multifocal narrowing of the cerebral arteries that resolves over days to weeks. This syndrome may be idiopathic or occur in special contexts, most often involving adrenergic or serotonergic overactivity. To the best of our knowledge, reve...

Vascular resistance and blood pressure (BP) are reduced during late normal pregnancy (Norm-Preg). In contrast, studies in human preeclampsia and in animal models of hypertension in pregnancy (HTN-Preg) have suggested that localized reduction in uterine perfusion pressure (RUPP) in late pregnancy is associated with increased systemic vascular resistance and BP; however, the vascular mechanisms i...