caa a22 4500 469079053 CHVBK 20180323132944.0 cr unu---uuuuu 170328e19920601xx s 000 0 eng 10.1007/BF00164578 doi (NATIONALLICENCE)springer-10.1007/BF00164578 Chronopharmacology of isoprenaline: the effects on rat plasma concentrations of large neutral amino acids depend on time of day for administration [Elektronische Daten] [Lennart Voog, Tomas Eriksson] Summary: This investigation was undertaken in order to test our hypothesis, that the endogenous circadian rhythms in large neutral amino acids (LNAAs) in plasma are partly regulated by β-adrenergic mechanisms. The β-adrenoceptor agonist isoprenaline, which is known to decrease the concentrations of rat plasma LNAAs, was given at several time-points over a full 24-h period intraperitoneally to rats, which were killed 1 h later. Isoprenaline, administered in the evening, decreased the plasma amino acid concentrations more than it did in the same doses given in the morning. Also the potency of isoprenaline was in this respect higher in the evening than in the morning. This finding, of a time-of-day dependent relationship between the effects of a β-adrenoceptor agonist and plasma LNAA concentrations, supports our hypothesis, that β-adrenergic mechanisms are involved in the endogenous regulation of the plasma LNAA rhythms. We suggest that the known endogenous circadian variation in sympathetic activity, which gives rise to a reciprocal rhythm in β-adrenoceptor responsiveness, could be one factor explaining that part of the circadian rhythm in plasma LNAA concentrations, which is not due to variations in food intake. Springer-Verlag, 1992 Large neutral amino acid nationallicence Chronopharmacology nationallicence Isoprenaline rat nationallicence Voog Lennart Department of Pharmacology, University of Gothenburg, P.O. Box 33031, S-40033, Gothenburg, Sweden aut Eriksson Tomas Department of Pharmacology, University of Gothenburg, P.O. Box 33031, S-40033, Gothenburg, Sweden aut Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 345/6(1992-06-01), 647-652 0028-1298 345:6<647 1992 345 210 https://doi.org/10.1007/BF00164578 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00164578 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Voog Lennart Department of Pharmacology, University of Gothenburg, P.O. Box 33031, S-40033, Gothenburg, Sweden aut NATIONALLICENCE 700 1- Eriksson Tomas Department of Pharmacology, University of Gothenburg, P.O. Box 33031, S-40033, Gothenburg, Sweden aut NATIONALLICENCE 773 0- Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 345/6(1992-06-01), 647-652 0028-1298 345:6<647 1992 345 210 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer