Regional blood flow measurement with pulsed Doppler flowmeter in conscious rat

Abstract

Development of techniques for the continuous measurement of regional blood flow and vascular resistance in intact small animals has been impeded primarily by the bulkiness of flow probes. The availability of an ultrasonic pulsed Doppler flowmeter system enabled us to construct miniaturized probes using 1-mm-diameter piezoelectric crystals that emit a 20-mHz signal and receive the reflected sound waves from passing blood cells. The finished flow probe is approximately 2.5-4 mm long and 2 mm in cross-sectional diameter with lumen diameters appropriate for the rat, ranging from 0.7 to 1.2 mm. This report describes the materials and methods involved in constructing and implanting the probes in rats to monitor renal, mesenteric, and hindquarter blood flow velocity. The accuracy of the pulsed Doppler method in detecting changes in regional blood flow and vascular resistance was established by the demonstration of a highly significant correlation between velocity recorded from the Doppler unit and volume flow recorded simultaneously. These data indicate that the ultrasonic pulsed Doppler flowmeter provides the opportunity to measure changes in regional blood flow and vascular resistance in a conscious freely moving rat.

Exercise changes regional vascular control by commissural NTS in spontaneously hypertensive rats

“…The leads of the flow probes were connected to a Doppler flowmeter (Department of Bioengineering, The University of Iowa, Iowa City, IA) for indirect blood flow measurement. More details about the Doppler technique, including the reliability of this method for estimation of the blood velocity have been previously described by Haywood et al (1981). Relative hindquarter and mesenteric vascular conductance were calculated as the ratio of Doppler shift and MAP.…”

Tonic inhibitory control exerted by opioid peptides in the paraventricular nuclei of the hypothalamus on regional hemodynamic activity in rats

“…At least 7 days later, the rats were re-anaesthetized with a mixture of ketamine ± xylazine (100 and 10 mg kg 71 , respectively, i.p., supplemented as required) and had pulsed Doppler¯ow probes (Haywood et al, 1981) implanted around the left renal and superior mesenteric arteries and the lower abdominal aorta, according to the method previously developed by and as we previously described (Bachelard & Pitre, 1995;Bachelard et al, 1997). After operation, the rats were given s.c. injections of ampicillin (150 mg kg 71 ) and¯unixin (1 mg kg 71 ) and allowed to recover for at least 7 days.…”

“…Changes in Doppler shift signals were calculated as percentage of the baseline level. The latter have been shown to be a reliable index of volume¯ow (Haywood et al, 1981;Wright et al, 1987) and are referred to as¯ows in the text. The Doppler shift and corresponding mean arterial blood pressure signals were used to calculate percentage changes in regional vascular conductances (Gardiner et al, 1990b).…”

Effect of T-2 toxin on regional blood flow and vascular resistance in the conscious rat

“…Rats (300-340 g) were anesthetized with a solution of ketamine (I 00 mgjml) and acepromazine ( 1 mg/ml) administered intramuscularly in combination in a volume of0.13 ml/ I 00 g body wt. Miniaturized Doppler flow probes (Valpey-Fisher) were implanted around the abdominal aorta, superior mesenteric artery, and the left renal artery according to the method described earlier by Haywood et al ( 1981 ). Briefly, a ventral midline laparotomy incision was made and 4-mm lengths of the lower abdominal aorta.…”