Adenosine A(3) receptors regulate heart rate, motor activity and body temperature.
OBJECTIVE
To examine the phenotype of mice that lack the adenosine A(3) receptor (A(3)R).


METHODS
We examined the heart rate, body temperature and locomotion continuously by telemetry over several days. In addition, the effect of the adenosine analogue R-N(6)-phenylisopropyl-adenosine (R-PIA) was examined. We also examined heat production and food intake.


RESULTS
We found that the marked diurnal variation in activity, heart rate and body temperature, with markedly higher values at night than during day time, was reduced in the A(3)R knock-out mice. Surprisingly, the reduction in heart rate, activity and body temperature seen after injection of R-PIA in wild type mice was virtually eliminated in the A(3)R knock-out mice. The marked reduction in activity was associated with a decreased heat production, as expected. However, the A(3)R knock-out mice, surprisingly, had a higher food intake but no difference in body weight compared to wild type mice.


CONCLUSIONS
The mice lacking adenosine A(3) receptors exhibit a surprisingly clear phenotype with changes in diurnal rhythm and temperature regulation. Whether these effects are due to a physiological role of A(3) receptors in these processes or whether they represent a role in development remains to be elucidated.
Yang
J N
JN
Department of Physiology & Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Wang
Y
Y
Garcia-Roves
P M
PM
Björnholm
M
M
Fredholm
B B
BB
D000241:Adenosine / Q000378:metabolism; D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D001835:Body Weight; D002940:Circadian Rhythm / Q000502:physiology; D004435:Eating; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009043:Motor Activity / Q000502:physiology*; D010641:Phenotype; D043684:Receptor, Adenosine A3 / Q000235:genetics / Q000378:metabolism*; D013686:Telemetry
D043684:Receptor, Adenosine A3; D000241:Adenosine