Comparison of telemetric and tail-cuff blood pressure monitoring in adrenocorticotrophic hormone-treated rats.
1. The aim of the present study was to validate a telemetric blood pressure (BP) monitoring system against tail-cuff blood pressure in both adrenocorticotrophic hormone (ACTH)- and sham-treated rats. In the statistical analyses, we first tested whether there was a detectable effect on systolic blood pressure (SBP) of 10 days treatment with ACTH compared with saline. Second, we compared results of telemetered and tail-cuff measurements and, third, we developed a novel method for estimating the relative power of the two techniques. 2. Twenty-three male Sprague-Dawley rats were randomly divided into two groups: (i) ACTH (100 microg/kg per day, s.c; n = 12) treated; or (ii) sham treated (0.9% saline, s.c; n = 11). Systolic BP was measured by the telemetric system (sampled for 10 s every 2 min) continuously for 4 h (n = 16) or for 30 min (n = 23) and also by the indirect tail-cuff method daily (n = 23). Data were compared within and between groups; ordinary least products (OLP) regression analysis was then performed to test for bias between the two methods. Sample size/power estimations were also performed. 3. Adrenocorticotrophic hormone treatment raised telemetered SBP by 11 mmHg (P < 0.001) compared with 14 mmHg (P < 0.001) using the tail-cuff method. There was no fixed or proportional bias between the two methods of measurement, as shown by regression analysis. Power calculations indicate that a minimum sample size of six gives a power of telemetered to tail-cuff of 0.84/0.86 = 0.98. The power of 4 h versus 30 min BP measurements was 0.99/0.82 = 1.2. 4. Telemetry gave very similar results to the tail-cuff method. Telemetry allows for a longer period of measurement, giving greater power to the study so that fewer animals are needed.
Fraser
T B
TB
Department of Medicine, St George Hospital, The University of New South Wales, Sydney, Australia.
Turner
S W
SW
Mangos
G J
GJ
Ludbrook
J
J
Whitworth
J A
JA
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D001795:Blood Pressure Determination / Q000379:methods*; D015924:Blood Pressure Monitors; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D013623:Tail; D013686:Telemetry / Q000379:methods*
D000324:Adrenocorticotropic Hormone