Document Detail

A pharmacodynamic turnover model capturing asymmetric circadian baselines of body temperature, heart rate and blood pressure in rats: challenges in terms of tolerance and animal-handling effects.
MedLine Citation:
PMID:  16328099     Owner:  NLM     Status:  MEDLINE    
This study presents development and behaviour of a feedback turnover model that mimics asymmetric circadian oscillations of body temperature, blood pressure and heart rate in rats. The study also includes an application to drug-induced hypothermia, tolerance and handling effects. Data were collected inn normotensive Sprague-Dawley rats, housed at 25 degrees C with a 12:12 hr light dark cycle (light on at 06:00 am) and with free access of food and water. The model consisted of two intertwined parallel compartments which captured a free-running rhythm with a period close to but not exactly 24 hrs. The free-running rhythm was synchronised to exactly 24 hrs by the environmental timekeeper (12:12 hr light on/off cycle) in experimental settings. The baseline model was fitted to a standardised 24-hr period derived from mean data of six animals over a period of nine consecutive days. The first-order rate constants related to the turnover of the baseline temperature, alpha and beta, were 0.026 min(-1) (+/-5%) and 0.0037 min(-1) (+/-3%). The alpha and beta parameters are approximately 2/transition time between day and night and 2/night time, respectively. The day:night timekeeper g(t), reference point T(ref) and amplitude were 0.053(+/-2%), 37.3(+/-0.02%) and 3.3% (+/-2%), respectively. Simulations with the baseline model revealed stable oscillations (free-running rhythm) in the absence of the timekeeper. This temperature-time profile was then symmetric and had a smaller amplitude, with a slightly shorter period and less pronounced temperature shift as compared to the profile in the presence of an external Timekeeper. Fitting the model to 96 hr mean profiles of blood pressure and heart rate from 10 control animals demonstrated the usefulness of the model. Simulations of the integrated temperature model succeeded in mimicking other modes of administration such as oral dosing.
Bj?rn S?llstr?m; Sandra A G Visser; Tomas Forsberg; Lambertus A Peletier; Ann-Christine Ericson; Johan Gabrielsson
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Journal of pharmacokinetics and pharmacodynamics     Volume:  32     ISSN:  1567-567X     ISO Abbreviation:  J Pharmacokinet Pharmacodyn     Publication Date:  2005 Dec 
Date Detail:
Created Date:  2005-12-12     Completed Date:  2006-04-13     Revised Date:  2009-11-03    
Medline Journal Info:
Nlm Unique ID:  101096520     Medline TA:  J Pharmacokinet Pharmacodyn     Country:  England    
Other Details:
Languages:  eng     Pagination:  835-59     Citation Subset:  IM    
PKPD section, Local Discovery Research Area CNS & Pain Control, AstraZeneca R&D S?dert?lje, B231, SE-151 85, S?dert?lje, Sweden.
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MeSH Terms
Administration, Oral
Adrenergic alpha-Agonists / administration & dosage,  blood,  pharmacokinetics
Analgesics / administration & dosage,  blood,  pharmacokinetics
Animal Husbandry / methods
Behavior, Animal / drug effects,  physiology
Blood Pressure / drug effects*,  physiology
Body Temperature Regulation / drug effects*,  physiology
Circadian Rhythm / physiology
Drug Tolerance
Heart Rate / drug effects*,  physiology
Injections, Subcutaneous
Models, Biological*
Rats, Sprague-Dawley
Time Factors
Reg. No./Substance:
0/Adrenergic alpha-Agonists; 0/Analgesics

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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