THE EFFECTS OF CATECHOLAMINES ON HEMORRHAGIC SHOCK IN DOGS

The effects of isoproterenol, dopamine, dobutamine and the combination of dopamine and dobutamine were compared by using forty-two mongrel dogs in hemorrhagic shock states. The combined use of dopamine and dobutamine was considered to be the most effective in the treatment of hemorrhagic shock in view of the small increase in heart rate, the large and steady increase in cardiac output, the maintenance in renal arterial blood flow and the mild increase in peripheral resistance

THROMBOXANE A2 AND HEMODYNAMIC-BIOCHEMICAL PARAMETERS IN CANINE ENDOTOXIN SHOCK

Prostaglandins participate in the pathophysiology of endotoxin shock; however, their exact role has not yet been clear. In this study, we investigated the role of the proaggregatory vasoconstrictor, thoromboxane A2 (T×A2), an arachidonic acid metabolite, during canine endotoxin shock. The central venous plasma levels of thromboxane B2 (T×B2), the stable metabolite of T×A2, was measured by radioimmunoassay. We also investigated the therapeutic effect of reduced glutathione (GSH), a potential cell-stabilizing sulfhydryl compound, in canine endotoxin shock. Sixty minutes after the intraveous administration of E. coli endotoxin (1 mg/kg), the plasma T×B2 levels were significantly increased from 68.8±49.0 pg/ml to 318.3±117.2 pg/ml (N=5) in the control group and from 67.9±68,4 pg/ml to 222.6±133.2 pg/ ml (N=5) in the GSH (300 mg/kg/hr) group. The levels in the GSH group were somewhat lower than in the control group for 60 to 180 minutes after the injection of endotoxin. Thromboxane A2 value appear not to relate to early thrombocytopenia and pulmonary hypertension but to relate to the change of late coagulopathy and of pulmonary vascular resistance. The administration of GSH suppressed the lactic acidemia significantly, however there was a much more decrease in the mean arterial pressure in the GSH group than in the control group. In addition, there was a tendency to inhibit the increase of the serum β-glucronidase activity in the GSH group

HEMODYNAMICS IN EXPERIMENTAL ENDOTOXIN SHOCK WITH CONTINUOUS ADMINISTRATION

Experimental endotoxin shock was induced with 4 mg/kg of purified endotoxin by continuous infusion instead of bolus injection in order to simulate the clinical condition. Abrupt decrease in the mean artery pressure and transient increase in the pulmonary artery pressure, which were usually seen in the initial stage accompanying the bolus injection of endotoxin, did not occur with continuous infusion. The superior mesenteric fraction rate of cardiac output (CO) in our study showed an increase, which was different from the small intestinal fraction rate of CO shown by Okada et αl. by the micro-sphere method (MS method) accompanying the bolus injection of endotoxin. These effects might be caused by the difference in the injection method and endotoxin dose. Measurements of the cardiac output, common carotid artery flow, renal artery flow and superior mesenteric artery flow proved that the largest reduction was observed in the renal blood flow

DIAZEPAM-INDUCED SUPPRESSION OF JAW OPENING REFLEX IN RATS

Effect of an i.p. injection of diazepam on the jaw opening reflex evoked by electrical stimuli applied to the tooth pulp innervated by mainly high threshold afferents and the lower lip innervated by low threshold afferents was investigated using Wistar albino rats. Small doses of diazepam, less than 2.5 mg/kg, suppressed to the same degree the jaw opening reflexes evoked by stimulation of tooth pulp or lower lip. However, when larger doses than 5.0 mg/kg were administered, the suppression of tooth pulp evoked jaw opening reflex was greater than that of lower lip-evoked one. In this case, the period of suppression of tooth pulp-evoked jaw opening reflex was longer than that of lower lip evoked one. It is concluded that (1) the pain relieving effect of diazepam appears only when larger doses than 5.0 mg/ kg are administered and that (2) the pain-relieving effect lasts longer than muscle-relaxative effect of diazepam

EFFECT OF CARDIAC OUTPUT ON PULMONARY SHUNT

The effect of cardiac output on pulmonary shunt was studied in living lungs of human patients and dogs which had alveoli and blood vessels, and also in artificial lung (bubble-type oxygenator) which, had no such structural factors. In spite of such a structural difference, quite similar results were observed in both living and artificial lungs, and this suggests that some common factors other than the change in blood vessels result in the change in pulmonary shunt. It was observed that pulmonary shunt increased as the saturation of mixed venous blood became higher. It was clarified that the oxygen receiving capacity of blood decreased as the oxygen saturation became higher, i.e., the amount of reduced hemoglobin became less. The reduction in oxygen-receiving capacity of blood results in the leduction in oxygen-transfer efficiency from alveoli to blood and hence pulmonary shunt increases, and this can be regarded as a kind of shunt-like effect. It can be concluded that the change in pulmonary shunt by cardiac output is not due to the change in the lung function but is caused by the change in the oxygen-receiving capacity of the mixed venous blood

AN EXPERIMENTAL STUDY ON THE EFFECT OF PLASMA EXPANDERS ON BLOOD COAGULABILITY

The effect of various plasma expanders on blood coagulation was studied using the thromboelastography (TEG). Solutions of 5, 10, 20, and 50% concentration of each expander (6% low molecular weight hydroxyethyl starch (6% Hespander®)*2, 3% dextran-40, 6% high molecular‘ weight hydroxyethyl starch (6 HES®)*3, and 6% dextran-70) or solvent (lactated Ringer solution and normal saline))) in blood were prepared and their coagulability was examined by TEG. In the low molecular weight plasma expanders (6% Hespander⑮ and 3% dextran 40), in general, the coagulability decreased when the concentration was increased. In the high molecular weight plasma expanders (6 HES® and 6% dextran-70), the coagulability increased slightly at low and high concentrations and the coagulability was reduced. As a conclusion, at clinically used concentrations of less than 20% in blood, changes in the TEG of the plasma expanders are minimum and have no clinical significance

FUNDAMENTAL STUDIES ON ELECTRIC STIMULATOR USED FOR ACUPUNCTURE ANALGESIA

In order to perform safe and effective electric stimulation in acupuncture analgesia or therapy, basic knowledge concerning the electric stimulator is required. If direct current is used, a negative square wave with a pulse duration of 0.5~1.5 msec should be applied to the needle electrode to perform elective stimulation. Negative current is more effective at lower amperage than positive current and the possible corrosion hazard by the positive current can be avoided

ANTAGONISM OF ACUPUNCTURE ANALGESIA BY NALOXONE IN UNCONSCIOUS MAN

The effects of acupuncture analgesia were studied using the change in halothane MAC in volunteers. Halothane MAC under electrical acupuncture stimulation was reduced to 86.2 ± 11.1% from the control value. After naloxone administration the level of the MAG was raised to the control level and the increment was 19.l ± 14.8%. Naloxone itself did not change the halothane MAC in the same subjects. These results suggest that the changes in halothane MAC under acupuncture stimulation are caused by the release of an endogenous analgesic substance in the brain