caa a22 4500 469078286 CHVBK 20180323132941.0 cr unu---uuuuu 170328e19920901xx s 000 0 eng 10.1007/BF00173553 doi (NATIONALLICENCE)springer-10.1007/BF00173553 Evidence for direct vasoconstrictor activity of melatonin in "pressurized” segments of isolated caudal artery from juvenile rats [Elektronische Daten] [B. Evans, R. Mason, V. Wilson] Summary: Responses of isolated, 60 mmHg ‘pressurized' segments of the distal caudal artery of adult and juvenile Wistar rats to melatonin and the selective α2-adrenoceptor agonist 5-bromo-6-[2-imidazolin-2-ylamino]-quinoxaline bitartrate (UK-14304) were examined using the Halpern pressure myograph. Melatonin showed no direct vasoconstrictor activity in vessels from adult rats, whereas UK-14304 produced moderate vasoconstriction (pD2- 7.43+-0.09). In the presence of phenylephrine-induced tone, melatonin produced a variable but small constrictor response (< 10µm reduction in diameter) in some vessels; the response to 1 gmol/l UK-14304 was less than in the absence of tone. In vessels isolated from juvenile rats, melatonin caused concentration-dependent vasoconstriction with a maximum response about 70% of the maximum response elicited by UK-14304. Vessels from juvenile rats were more sensitive to melatonin(pD2- 9.40+-0.07) than they were to UK-14304 (pD2 -8.12+-0.14). In the presence of phenylephrine-induced tone, the vasoconstrictor responses to both melatonin and IK-14304 were markedly less; the sensitivity to melatonin was not different from that seen in the absence of tone. These findings indicate that ‘pressurized' segments of the isolated distal caudal artery may provide a simple and convenient, functional model of melatonin receptors. The findings also appear to implicate melatonin in thermoregulatory processes in juvenile rats. Springer-Verlag, 1992 Melatonin nationallicence UK-14304 nationallicence Rat distal caudal artery nationallicence Juvenile rats nationallicence Evans B. Department of Physiology and Pharmacology, The University of Nottingham Medical School, Queen's Medical Centre, Nottingham, England aut Mason R. Department of Physiology and Pharmacology, The University of Nottingham Medical School, Queen's Medical Centre, Nottingham, England aut Wilson V. Department of Physiology and Pharmacology, The University of Nottingham Medical School, Queen's Medical Centre, Nottingham, England aut Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 346/3(1992-09-01), 362-365 0028-1298 346:3<362 1992 346 210 https://doi.org/10.1007/BF00173553 text/html Onlinezugriff via DOI 1 brief-communication jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00173553 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Evans B. Department of Physiology and Pharmacology, The University of Nottingham Medical School, Queen's Medical Centre, Nottingham, England aut NATIONALLICENCE 700 1- Mason R. Department of Physiology and Pharmacology, The University of Nottingham Medical School, Queen's Medical Centre, Nottingham, England aut NATIONALLICENCE 700 1- Wilson V. Department of Physiology and Pharmacology, The University of Nottingham Medical School, Queen's Medical Centre, Nottingham, England aut NATIONALLICENCE 773 0- Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 346/3(1992-09-01), 362-365 0028-1298 346:3<362 1992 346 210 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer