Actividad rítmica espontánea en vasos de placenta humana: ¿Un marcapaso fisiológico en los vasos sanguíneos?

Background: Placental vessels are not innervated. Therefore the vasomotor activity and vascular tone is not regulated by the nervous system. Aim: To assess the existence of pacemaker mechanisms related to rhythmic motor activity of blood vessels. Material and methods: Isometric contractions of rings...

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Autores principales:	Huidobro-Toro,Juan Pablo G, González C,Rolando, Varas F,José Alejandro, Rahmer O,Alejandro, González A,Rolando
Lenguaje:	Spanish / Castilian
Publicado:	Sociedad Médica de Santiago 2001
Materias:	Spontaneous rhythmic activity umbilical veins chorionic vessels vascular pacemaker spontaneous rhythmic contractions
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0034-98872001001000001
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spelling	oai:scielo:S0034-988720010010000012005-11-14Actividad rítmica espontánea en vasos de placenta humana: ¿Un marcapaso fisiológico en los vasos sanguíneos?Huidobro-Toro,Juan Pablo GGonzález C,RolandoVaras F,José AlejandroRahmer O,AlejandroGonzález A,Rolando Spontaneous rhythmic activity umbilical veins chorionic vessels vascular pacemaker spontaneous rhythmic contractions Background: Placental vessels are not innervated. Therefore the vasomotor activity and vascular tone is not regulated by the nervous system. Aim: To assess the existence of pacemaker mechanisms related to rhythmic motor activity of blood vessels. Material and methods: Isometric contractions of rings from umbilical and chorionic vessels of term human placentas were monitored. Results: Recordings of the circular layer of chorionic and umbilical vessels revealed rhythmic spontaneous contractions with a frequency of 1,4±0,05 cycles/min, the duration of each cycle was 42,8±0,24 s (n=12). The amplitude of contractions was larger in veins than in arteries, predominating in umbilical vein biopsies, proximal to the fetus. Both the frequency and the amplitude of contractions were relatively constant during the first 30 min. However, after an hour, the frequency declined while the amplitude increased. The absence of the endothelium neither modified the frequency nor the amplitude of the rhythmic activity. Blockage of voltage dependent sodium channels or calcium channels did not alter the frequency of spontaneous contractions, although their magnitude was reduced. Glibenclamide, an ATP-dependent K+ channel blocker or the blockade of gap junctions ablated the frequency and amplitude of spontaneous contractions. Conclusions: We propose that rhythmic contractions are triggered by pacemaker cells located in the circular layer of the smooth muscle of blood vessels and spread via gap junctions; they likely contribute to the control of blood flow (Rev Méd Chile 2001; 129: 1105-12)info:eu-repo/semantics/openAccessSociedad Médica de SantiagoRevista médica de Chile v.129 n.10 20012001-10-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0034-98872001001000001es10.4067/S0034-98872001001000001
institution	Scielo Chile
collection	Scielo Chile
language	Spanish / Castilian
topic	Spontaneous rhythmic activity umbilical veins chorionic vessels vascular pacemaker spontaneous rhythmic contractions
spellingShingle	Spontaneous rhythmic activity umbilical veins chorionic vessels vascular pacemaker spontaneous rhythmic contractions Huidobro-Toro,Juan Pablo G González C,Rolando Varas F,José Alejandro Rahmer O,Alejandro González A,Rolando Actividad rítmica espontánea en vasos de placenta humana: ¿Un marcapaso fisiológico en los vasos sanguíneos?
description	Background: Placental vessels are not innervated. Therefore the vasomotor activity and vascular tone is not regulated by the nervous system. Aim: To assess the existence of pacemaker mechanisms related to rhythmic motor activity of blood vessels. Material and methods: Isometric contractions of rings from umbilical and chorionic vessels of term human placentas were monitored. Results: Recordings of the circular layer of chorionic and umbilical vessels revealed rhythmic spontaneous contractions with a frequency of 1,4±0,05 cycles/min, the duration of each cycle was 42,8±0,24 s (n=12). The amplitude of contractions was larger in veins than in arteries, predominating in umbilical vein biopsies, proximal to the fetus. Both the frequency and the amplitude of contractions were relatively constant during the first 30 min. However, after an hour, the frequency declined while the amplitude increased. The absence of the endothelium neither modified the frequency nor the amplitude of the rhythmic activity. Blockage of voltage dependent sodium channels or calcium channels did not alter the frequency of spontaneous contractions, although their magnitude was reduced. Glibenclamide, an ATP-dependent K+ channel blocker or the blockade of gap junctions ablated the frequency and amplitude of spontaneous contractions. Conclusions: We propose that rhythmic contractions are triggered by pacemaker cells located in the circular layer of the smooth muscle of blood vessels and spread via gap junctions; they likely contribute to the control of blood flow (Rev Méd Chile 2001; 129: 1105-12)
author	Huidobro-Toro,Juan Pablo G González C,Rolando Varas F,José Alejandro Rahmer O,Alejandro González A,Rolando
author_facet	Huidobro-Toro,Juan Pablo G González C,Rolando Varas F,José Alejandro Rahmer O,Alejandro González A,Rolando
author_sort	Huidobro-Toro,Juan Pablo G
title	Actividad rítmica espontánea en vasos de placenta humana: ¿Un marcapaso fisiológico en los vasos sanguíneos?
title_short	Actividad rítmica espontánea en vasos de placenta humana: ¿Un marcapaso fisiológico en los vasos sanguíneos?
title_full	Actividad rítmica espontánea en vasos de placenta humana: ¿Un marcapaso fisiológico en los vasos sanguíneos?
title_fullStr	Actividad rítmica espontánea en vasos de placenta humana: ¿Un marcapaso fisiológico en los vasos sanguíneos?
title_full_unstemmed	Actividad rítmica espontánea en vasos de placenta humana: ¿Un marcapaso fisiológico en los vasos sanguíneos?
title_sort	actividad rítmica espontánea en vasos de placenta humana: ¿un marcapaso fisiológico en los vasos sanguíneos?
publisher	Sociedad Médica de Santiago
publishDate	2001
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0034-98872001001000001
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Actividad rítmica espontánea en vasos de placenta humana: ¿Un marcapaso fisiológico en los vasos sanguíneos?

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