[Measurement of cardiac output in waking rats using a Doppler ultrasonic technic]. / Izmerenie serdechnogo vybrosa u bodrstvuiushchikh krys s pomoshch'iu ul'trazvukovoi dopplerovskoi tekhniki.

The ultrasound Doppler technique was used for the determination of cardiac output in conscious Wistar rats. The cuff probes were placed on the ascending aorta and calibrated with the radioactive microsphere technique. The results of experiments show that Doppler ultrasound technique determines the cardiac output with high linearity. The possibility of using both methods in one and the same animal was also confirmed.

[Hemodynamic changes in immobilization stress]. / Izmeneniia gemodinamiki pri immobilizatsionnom stresse.

In chronic experiments on 75 Wistar, August and randombred rats hemodynamic changes were examined during 30-hour immobilization stress. The ECG was recorded and arterial blood pressure measured. The basic hemodynamic characteristics were determined with the help of the previously implanted ultrasonic blood flow probes. Analysis of hemodynamic changes in animals resistant, adapted and prone to stress demonstrated that changes in the total peripheral resistance play the leading role in the disturbance of the arterial blood pressure control. It was established that a progressive lowering of arterial blood pressure resulting from the abruptly reduced total peripheral resistance is the main and the most frequent cause of death of animals exposed to immobilization stress. At the same time the cardiac hemodynamic component may play an essential role in the mechanism of death. This component may include either progressive bradycardia or a combination of an ischemic myocardial damage and reduced total peripheral resistance.

[Analysis of the role of endogenous opioid peptides in experimental hypertension]. / Analiz roli éndogennykh opioidnykh peptidov pri éksperimental'noi gipertenzii.

In Wistar rats, spontaneously hypertensive rats (SHR) and in rats with one-kidney Goldblatt hypertension, naloxone (0.1 and 1.0 mg/kg) evoked the 10 mm Hg increase of blood pressure in the two groups of hypertensive rats, did not change sensitivity of their baroreceptor reflex but facilitated the reflex in normotensive rats. A possible role of endogenous peptides in blood pressure control is discussed in relation to their ability to stimulate mu- and delta-opiate receptors.

[Blocking by naloxone of the antihypertensive effect of clonidine in hypertensive and normotensive animals]. / Blokirovka naloksonom antigipertenzivnogo éffekta klonidina u gipertenzivnykh i normotenzivnykh zhivotnykh.

Antagonism between cardiovascular effects of clonidin (10-30 micrograms/kg) and naloxon (0.15-1.0 mg/kg) was studied on anesthetized spontaneously hypertensive rats (SHR) as compared to Wistar Kyoto (WKY) rats and on awake cats. Naloxon was shown to completely block the clonidin hypotensive effect in SHR and cats and to partially block it in WKY rats. In some experiments, naloxon was administered after the blockade of peripheral M-cholinoreceptors by metacin (2 mg/kg). In these experiments naloxon evoked elevation of blood pressure, cardiac output and heart rate (in cats). It is concluded that the opioid link participates in the development of clonidin-evoked bradycardia and hypotension both in hypertensive and in normotensive animals.