ISSN:
1432-1912
Keywords:
Endothelium
;
Isolated visceral, vascular and bronchial smooth muscle
;
Isolated perfused vascular beds
;
Isolated hearts
;
Isolated atria
;
Blood pressure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary (1) The actions of porcine endothelin (ET), an endothelium-derived vasoconstrictor peptide, have been investigated in several in vitro smooth and cardiac muscle preparation as well as on the blood pressure of anaesthetized rats and rabbits. (2) In isolated visceral smooth muscles (guinea pig ileum, rat colon and uterus, rabbit jejunum) ET caused a long-lasting contraction which persisted after repeated rinsing. ET did not interfere with the spontaneous phasic activity of the rabbit jejunum or with contractions evoked by histamine or carbachol. (3) ET contracted isolated blood vessels (portal vein of guinea-pig and rat). In isolated perfused organs (rabbit ear, guinea-pig lung, rat mesentery and hindpaw) ET led to a long-lasting vasoconstriction. In the isolated perfused guinea-pig lung ET caused vaso- and bronchoconstriction. (4) ET produced a long-lasting positive inotropic effect in spontaneously beating isolated guinea-pig atria. The positive inotropic action of strophanthin was augmented in the presence of ET. (5) In the isolated perfused guinea-pig and rat hearts the prominent effect of ET was a long-lasting coronary vasoconstriction. (6) Pithed rats responded to i.v. injection of ET with a long-lasting increase in blood pressure. In pentobarbitone anaesthetized rats pretreated either with atropine, with guanethidine plus atropine, or with guanethidine plus atropine plus indomethacin, the long-lasting increase in blood pressure was smaller than in pithed rats whereas the initial short-lasting decrease in blood pressure was more pronounced; in pentobarbitone anaesthetized rabbits endothelin caused bronchoconstriction, a decrease in blood pressure and a pronounced increase in central venous pressure possibly resulting from pulmonary or coronary artery constriction or a combination of both effects. (7) Neither topical nor systemic application of ET influenced the bleeding time from small rat mesenteric arteries. (8) The general effect of ET on visceral, bronchial and vascular smooth muscles was a longlasting contraction. Despite its general constrictor potency seen in isolated vascular preparations ET can cause a transient decrease in arterial blood pressure in anaesthetized rats and rabbits. The role of ET when released from vascular endothelium remains a matter of speculation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00169684
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