Radiotelemetry in Cardiovascular Chronopharmacology in Transgenic and Knock- out Rats and Mice

S53. 5 Radiotelemetry in Cardiovascular Chronopharmacology in Transgenic and Knockout Rats and Mice BjÊern Lemmer; Institute of Experimental and Clinical Pharmacology and Toxico-l ogy, University of Heidelberg; Maybachstr. 14, 68169 Mannheim, Germany In freely moving rodents radiotelemetry has improvedknowledge on circadian regulation of cardiovascular system ( blood pressure BP, heart rate HR, electrocardiogram ECG, activity MA, body temperature BT) . Radiotelemetry ( Data Sc-i ences) was used in strains of normotensive ( Sprague-Daw ley; Wistar-Kyoto ) , hypertensive/ transgenic ( SHR; TGR ( mREN2) 27 ) rats, C57 wild type and eNOS/knock out mice. Experiments were performed under 12:12h light : darkness ( LD) , total darkness ( DD, i. e. free-run) , and after phase-shif t of LD cycle by + 6 hrs. Rhythm data was analysed with Chronos-Fit (Zuther &Lemmer, 2004) , f itting Fourier series to data of single/ grouped animals, Power spectrum and actogram are implemented. Significant circadian rhythms were present in all rat/ mouse strains. Since rodents are nigh-t active peak values in BP, HR, ECG, MA and BT were at night, except in TGR ( with additional mouse renin gene) w ith peak in BP in rest phase. In rats andmice rhythms persisted in DD, indica-t ing an endogenous rhythm, in rats rhythms were abolished af ter lesioning of master clock in nucleus suprachiasmaticus. Data evidence that the cardiovascular system is under control of a circadian clock. Telemetry Rat Mice Circadian