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Comparison Of Telemetric And Tail‐Cuff Blood Pressure Monitoring In Adrenocorticotrophic Hormone‐Treated Rats
Author(s) -
Fraser Tafline B,
Turner Steven W,
Mangos George J,
Ludbrook John,
Whitworth Judith A
Publication year - 2001
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.2001.03531.x
Subject(s) - adrenocorticotrophic hormone , blood pressure , cuff , medicine , saline , adrenocorticotropic hormone , endocrinology , anesthesia , cardiology , hormone , surgery
SUMMARY 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 μ g/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.