INTERACTION BETWEEN ATRIAL NATRIURETIC FACTOR AND OUABAIN: VASCULAR REACTIVITY TO NORADRENALINE IN PENTOBARBITAL ANAESTHETIZED DOGS

1. The influence of intra-arterial infusion of rat atrial natriuretic factor (ANF 8-33) and/or ouabain on the vascular responses to noradrenaline was investigated in the denervated and flow-controlled hindlimb preparations in pentobarbital anaesthetized dogs. 2. During the continuous infusions of ANF (30-40 min) vascular responses to noradrenaline were significantly depressed. Subsequent infusion of ouabain together with ANF (50-60 min) reversed and restored the vascular reactivity to the control levels. Hypotension produced by ANF infusion was partially reversed during the simultaneous infusions of both the agents. 3. In a separate series of experiments, in which ouabain was first infused (50-60 min) vascular responses to noradrenaline were significantly enhanced. Subsequent infusions of ANF (plus ouabain) even up to 60 min or longer failed to alter the enhanced vascular responsiveness facilitated by ouabain. 4. The present studies demonstrate a physiological antagonism between ANF and ouabain and such a phenomenon could account for the previous observation that vascular reactivity to noradrenaline was progressively enhanced after acute blood volume expansion. Whereas plasma levels of both ANF and ouabain-like inhibitor(s) of the sodium pump are elevated after volume expansion, inhibitory effects of ANF on the vascular smooth muscle may be compromised in the presence of an Na+ pump inhibitor(s).     

Pulmonary-artery Cineangiocardiography and Echocardiography for Detection of Cardiac Sources of Cerebral Embolism

ABSTRACT Sixty-two patients with ischemic stroke possibly due to embolism of cardiac origin were investigated by pulmonary artery-cineangiography (PACAC) and echocardiography (UCG) to detect intracardiac thrombi. The proportion of intracardiac thrombi found by PACAC was 31% and by UCG 15%. The presence or absence of atrial fibrillation correlated well with PACAC findings of an intraventricular clot but poorly with UCG. Similarly, there was a significant association between ischemic heart disease and intraventricular thrombi detected by PACAC investigations but not with the results obtained by UCG. PACAC seems superior to UCG in the detection of intracardiac thrombi after possible embolic stroke.     

The Correlation between Electroencephalographical and Neuropathological Findings in Acute Stage of Cerebrovascular Disease

Abstract: A study was conducted on the electroencephalographical and neuropathological correlations on 96 cases of cerebrovascular disease in order to elucidate the reasons why EEGs are often misleading in the diagnosis of location and size of cerebrovascular lesions.
The study showed that EEG findings are particularly misleading when the lesions were in the locations as follows: 1) subcortical deep infarctions, 2) cortical infarctions occupying a small proportion of cerebral convexity, or involving an entire hemisphere, or affecting the right hemisphere, 3) basilar thrombosis and infratentorial hemorrhage (primary or secondary to supratentorial lesions). The pathophysiological significance of these results has been discussed.     

Measurement of cerebral vascular extraction fractions in the rat using intracarotid injection techniques

A small volume (5 μl) common carotid arterial injection method is described for the quantitation of cerebral vascular extraction fractions (E_t) of diffusion limited tracer molecules in the rat. The method is a modification of a technique diffusion duced by Oldendorf and widely used for the study of blood-brain barrier phenomena. While the Oldendorf technique has proven valuable for estimating the relative permeabilities of substances, it is limited in measuring E_t under conditions of physiologically or pharmacologically altered permeability or blood flow. The method described in this paper — using a small volume (5 μl) common carotid injection, a freely diffusible reference tracer, [¹⁴C]butanol, and a 5 sec circulation time — allows for measurements of E_t that reflect changes in blood flow and small differences in permeability. The modified method is important for the study of the regulation of cerebral vascular permeability and flow in an inexpensive animal model.     

Genes,stress and the heart

Effects of stress and its relationship to coronary morbidity and mortality are modified by genetic variation between people. We do not uniformly react to stress, nor do we create equally stressful living environments. The underlying causes of such individual variation are, in part, heritable. Two possible mechanisms through which genetic variation modulates the link between stress and coronary disease are cardiovascular stress reactivity and coronary-prone personality. Both possess characteristics of genetic markers: they are stable, familial, and heritable; they associate with the disease and are prospectively predictive of it. Twin-family data on cardiovascular stress reactivity and coronary-prone personality provide instructive illustrations of the interrelationship of genes, stress, and the heart.     

Channges in regional cerebral blood flow after hyperventilation in the pig with an induced focal cerebral contusion

Summary Changes in regional cerebral blood flow in anaesthetized pigs with an induced focal cerebral contusion were studied before and after two grades of hyperventilation. A reduction in arterial tension of CO₂ with 0.70mmHg and a further reduction of 0.55mmHg did not change the CO₂ reactivity. Reactivity in both injured and macroscopically normal regions was the same, revealing an average of 39.3% flow change per kPa change in CO₂ tension. Regions with low flow after the contusion had an equally big reduction apparently leading to hypoxia because global metabolic rate was unchanged.     

Evaluation of Functional Capacity after Stroke as a Basis for Active Intervention

ABSTRACT This paper describes further testing of an Activity Index introduced by Hamrin & Wohlin, which was designed especially to evaluate the functional capacity of patients after stroke. The results of reliability tests and validation procedures are presented, in particular in comparison with the internationally well known Katz Index of Independence in Activities of Daily Living. The standardised item alpha reliability coefficient for the Activity Index was 0.97 for the total score (n= 231) and the corresponding value for the Katz Index of ADL was 0.94. Using factor analysis with four factors, 88.3% of the variances of the 16 variables of the Activity Index could be explained, and the different variables were found to have a logical distribution between the factors. In a two-factor analysis of the Katz Index of ADL, 89.6% of the variance of the six variables could be explained, and the hierarchical structure of the test was recognised. Compared with the Katz Index of ADL, the Activity Index had a higher predictive capacity and it also better measured changes in the patient's functional ability between different test occasions.