THE ENDOGENOUS μ-OPIOID AGONISTS,ENDOMORPHIN 1 AND 2, HAVE VASODILATOR ACTIVITY IN THE HINDQUARTERS VASCULAR BED OF THE RAT

Endomorphin 1 and endomorphin 2 are newly-discovered endogenous ligands for the μ-opioid receptor. In the present study, responses to intra-arterial injections of endomorphin 1 and 2 were investigated in the hindquarters vascular bed of the rat. Under constant-flow conditions, endomorphin 1 and 2 induced dose-dependent decreases in hindquarters perfusion pressure when injected in doses of 3–100 nmol into the hindquarters perfusion circuit. Vasodilator responses to endomorphin 1 and 2 and met-enkephalin were attenuated by the opioid receptor antagonist naloxone (2 mg/kg i.v.) at a time when vasodilator responses to isoproterenol were not altered. In terms of relative vasodilator activity, endomorphin 1 and 2 were similar to ATP, 100-fold less potent than isoproterneol, and 10,000-fold less potent than acetylcholine. These data demonstrate that endomorphin 1 and 2 have significant naloxone-sensitive vasodilator activity in the hindquarters vascular bed of the rat. © 1997 Elsevier Science Inc.     

THE COPEPODA OF THE WU-L1 LAKE, WU-SIH, KIANGSU PROVINCE. Ⅱ. CYCLOPOIDA

This is the second part of a series of papers dealing with the Copepoda-fauna of theWu-Li Lake, Wu-Sih, Kiangsu Province, China. It comprises 21 species of Cyclopoida,of which 5 species (those marked with an asterisk in the list) are for the first time re-corded in China and two species of Tropocyclops are found to be new to science. All     

A SURVEY OF THE HOLARCTIC LINYPHIIDAE （ARANEAE）, OF THE ERIGONINE GENUS ZORNELLA JACKSON, 1932

The Holarctic erigonid genus Zornella has been surveyed. Four spedes are recognized in this genus, two Palaearctic： Z. aultrigera （L. Koch, 11879） ＆ Z. orientalis sp. nov., and two Nearcfic： Z. arrnata （Banks, 1906） ＆ Z. ayptodon Chamherlin, 1920. It is demouslrated that neither nearcfic species is agnspedtic with Z. atltrigera as was thought by Holm and other authors. Z. sp. nov. is describcd from northeastern Siberia. All of the species are illustrated and their distributions mapped.     

THE DISCOVERY OF THE CRIBRIFORM PLATE IN SINOCONODON YOUNCI (TRICONODONTA,MAMMALIA)

ThepresenceofacribriformplateinlivingplacentalsandthemarsupialsandabsenceinmonotremesmayimplythatmammalsarediphyleticandtheoriginofcribriformplatetookplacewithinthcMammalia.Buttheconc1usioncamefromthe1ivingmammalsonly,andhasnotbeensupportedbypalaeontologicalevidence.Itsappearanceinoneoftheoldestandthemostprimitivemammals,Sinoconodon,possiblysuggeststhatthecribriformplatemayoccurearlier,i.e.inthetimeofthetransitionfromtheadvancedmammal-likereptiles,Cynodontia,tothetruemammals,andthatthedistrib…