Piet Borgdorff

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Studies on the nervous or humoral control of total peripheral resistance are often complicated by concomitant changes in cardiac output. We studied the influence of cardiac output on peripheral resistance in the absence of modulating reflexes. In barodenervated and vagotomized cats, cardiac output was varied by graded inferior caval vein occlusion or by(More)
Regular fluctuations in pupil size of the cat were measured and the properties, nervous pathways, and origin of these oscillations were investigated. The rhythm of pupil movements under control conditions appeared to be either locked to the central respiratory cycle or to the artificial ventilatory cycle. These movements were only seen in lightly(More)
BACKGROUND Cardiopulmonary bypass and hemodialysis often cause hypotension. We investigated a possible role of pump-induced platelet activation with consequent serotonin release. METHODS AND RESULTS In rats, a heparin-coated extracorporeal shunt was placed between the proximal part of a carotid artery and the distal part of a femoral artery. Autoperfusion(More)
The interaction between autoregulation and baroregulation and its effect on the gains of the short-term pressure regulatory system was studied by performing both open- and closed-loop experiments in the same five anesthetized, vagotomized dogs, and by analyzing the data making use of a new model. With carotid pressure constant (no baroregulation) the(More)
BACKGROUND The aim of this study was to develop a model for hemodialysis (HD) in small animals using conventional dialysis equipment that would allow the intravital microscopic observation of leukocyte-endothelial interactions in vivo. METHODS Cuprophan dialyzers were adapted to obtain a similar ratio of membrane area to blood volume as in clinical HD. A(More)
We recently found that central administration of the cholinesterase inhibitor paraoxon lowered blood pressure substantially. It was postulated that the decrease in pressure was mediated by a reduction of sympathetic outflow. In the present study, efferent splanchnic nerve activity in anaesthetized and paralysed cats was recorded, and quantified by measuring(More)
An implantable nerve cooler has been constructed to block cervical vago-sympathetic activity in the exercising dog reversibly. An insulated gilt brass container implanted around the nerve is perfused with cooled alcohol via silicone tubes. The flow of alcohol is controlled by an electromagnetic valve to keep nerve temperature at the required value. Nerve(More)
BACKGROUND The sum of undesirable side effects, occurring during haemodialysis (HD), is called bio-incompatibility. Concerning platelets, both an increase in the expression of the cell surface marker P-selectin (CD62p) and release of the intracellular granule product platelet factor 4 (PF4) have been described. However, as PF4 is also abundantly present on(More)
Coronary blood flow responds uniquely to changes in myocardial demand, regardless of the stimulus. If adenosine mediates this response, interstitial fluid adenosine concentration should also change in parallel with myocardial oxygen consumption and coronary blood flow during alterations of cardiac work. We tested this hypothesis by measuring coronary blood(More)
BACKGROUND Migraine patients are at an increased risk for stroke, as well as other thromboembolic events. This warrants further study of the role of platelets in a proportion of migraine patients. OBJECTIVE To extend the "platelet hypothesis" using literature data and observations made in a rat model of shear stress-induced platelet aggregation. Such(More)