Gastroduodenal resistance and neural mechanisms involved in saline flow decrease elicited by acute blood volume expansion in anesthetized rats
We have previously demonstrated that blood volume (BV) expansion decreases saline flow through the gastroduodenal (GD) segment in anesthetized rats (Xavier-Neto J, dos Santos AA & Rola FH (1990) Gut, 31: 1006-1010). The present study attempts to identify the site(s) of resistance and neural mech...
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| Format: | Article |
| Language: | English |
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Associação Brasileira de Divulgação Científica
1997-01-01
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| Series: | Brazilian Journal of Medical and Biological Research |
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| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1997001000019 |
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| author | Graça J.R.V. Gondim F. de-A.A. Cavalcante D.I.M. Xavier-Neto J. Messias E.L.M. Rego M.C.V. Marques J.A.P. Santos A.A. Rola F.H. |
| author_facet | Graça J.R.V. Gondim F. de-A.A. Cavalcante D.I.M. Xavier-Neto J. Messias E.L.M. Rego M.C.V. Marques J.A.P. Santos A.A. Rola F.H. |
| author_sort | Graça J.R.V. |
| collection | DOAJ |
| description | We have previously demonstrated that blood volume (BV) expansion decreases saline flow through the gastroduodenal (GD) segment in anesthetized rats (Xavier-Neto J, dos Santos AA & Rola FH (1990) Gut, 31: 1006-1010). The present study attempts to identify the site(s) of resistance and neural mechanisms involved in this phenomenon. Male Wistar rats (N = 97, 200-300 g) were surgically manipulated to create four gut circuits: GD, gastric, pyloric and duodenal. These circuits were perfused under barostatically controlled pressure (4 cmH2O). Steady-state changes in flow were taken to reflect modifications in circuit resistances during three periods of time: normovolemic control (20 min), expansion (10-15 min), and expanded (30 min). Perfusion flow rates did not change in normovolemic control animals over a period of 60 min. BV expansion (Ringer bicarbonate, 1 ml/min up to 5% body weight) significantly (P<0.05) reduced perfusion flow in the GD (10.3 ± 0.5 to 7.6 ± 0.6 ml/min), pyloric (9.0 ± 0.6 to 5.6 ± 1.2 ml/min) and duodenal (10.8 ± 0.4 to 9.0 ± 0.6 ml/min) circuits, but not in the gastric circuit (11.9 ± 0.4 to 10.4 ± 0.6 ml/min). Prazosin (1 mg/kg) and yohimbine (3 mg/kg) prevented the expansion effect on the duodenal but not on the pyloric circuit. Bilateral cervical vagotomy prevented the expansion effect on the pylorus during the expansion but not during the expanded period and had no effect on the duodenum. Atropine (0.5 mg/kg), hexamethonium (10 mg/kg) and propranolol (2 mg/kg) were ineffective on both circuits. These results indicate that 1) BV expansion increases the GD resistance to liquid flow, 2) pylorus and duodenum are important sites of resistance, and 3) yohimbine and prazosin prevented the increase in duodenal resistance and vagotomy prevented it partially in the pylorus |
| first_indexed | 2024-12-12T14:02:52Z |
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| institution | Directory Open Access Journal |
| issn | 0100-879X 0034-7310 |
| language | English |
| last_indexed | 2024-12-12T14:02:52Z |
| publishDate | 1997-01-01 |
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| series | Brazilian Journal of Medical and Biological Research |
| spelling | doaj.art-378ed194bb404beea37a6fd35d52fb932022-12-22T00:22:17ZengAssociação Brasileira de Divulgação CientíficaBrazilian Journal of Medical and Biological Research0100-879X0034-73101997-01-01301012571256Gastroduodenal resistance and neural mechanisms involved in saline flow decrease elicited by acute blood volume expansion in anesthetized ratsGraça J.R.V.Gondim F. de-A.A.Cavalcante D.I.M.Xavier-Neto J.Messias E.L.M.Rego M.C.V.Marques J.A.P.Santos A.A.Rola F.H.We have previously demonstrated that blood volume (BV) expansion decreases saline flow through the gastroduodenal (GD) segment in anesthetized rats (Xavier-Neto J, dos Santos AA & Rola FH (1990) Gut, 31: 1006-1010). The present study attempts to identify the site(s) of resistance and neural mechanisms involved in this phenomenon. Male Wistar rats (N = 97, 200-300 g) were surgically manipulated to create four gut circuits: GD, gastric, pyloric and duodenal. These circuits were perfused under barostatically controlled pressure (4 cmH2O). Steady-state changes in flow were taken to reflect modifications in circuit resistances during three periods of time: normovolemic control (20 min), expansion (10-15 min), and expanded (30 min). Perfusion flow rates did not change in normovolemic control animals over a period of 60 min. BV expansion (Ringer bicarbonate, 1 ml/min up to 5% body weight) significantly (P<0.05) reduced perfusion flow in the GD (10.3 ± 0.5 to 7.6 ± 0.6 ml/min), pyloric (9.0 ± 0.6 to 5.6 ± 1.2 ml/min) and duodenal (10.8 ± 0.4 to 9.0 ± 0.6 ml/min) circuits, but not in the gastric circuit (11.9 ± 0.4 to 10.4 ± 0.6 ml/min). Prazosin (1 mg/kg) and yohimbine (3 mg/kg) prevented the expansion effect on the duodenal but not on the pyloric circuit. Bilateral cervical vagotomy prevented the expansion effect on the pylorus during the expansion but not during the expanded period and had no effect on the duodenum. Atropine (0.5 mg/kg), hexamethonium (10 mg/kg) and propranolol (2 mg/kg) were ineffective on both circuits. These results indicate that 1) BV expansion increases the GD resistance to liquid flow, 2) pylorus and duodenum are important sites of resistance, and 3) yohimbine and prazosin prevented the increase in duodenal resistance and vagotomy prevented it partially in the pylorushttp://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1997001000019blood volume expansiongastroduodenal resistanceduodenumpylorus!-- $MVD$:face("Symbol") --<FONT FACE=Symbol>a</font>-blockersvagotomy |
| spellingShingle | Graça J.R.V. Gondim F. de-A.A. Cavalcante D.I.M. Xavier-Neto J. Messias E.L.M. Rego M.C.V. Marques J.A.P. Santos A.A. Rola F.H. Gastroduodenal resistance and neural mechanisms involved in saline flow decrease elicited by acute blood volume expansion in anesthetized rats Brazilian Journal of Medical and Biological Research blood volume expansion gastroduodenal resistance duodenum pylorus !-- $MVD$:face("Symbol") --<FONT FACE=Symbol>a</font>-blockers vagotomy |
| title | Gastroduodenal resistance and neural mechanisms involved in saline flow decrease elicited by acute blood volume expansion in anesthetized rats |
| title_full | Gastroduodenal resistance and neural mechanisms involved in saline flow decrease elicited by acute blood volume expansion in anesthetized rats |
| title_fullStr | Gastroduodenal resistance and neural mechanisms involved in saline flow decrease elicited by acute blood volume expansion in anesthetized rats |
| title_full_unstemmed | Gastroduodenal resistance and neural mechanisms involved in saline flow decrease elicited by acute blood volume expansion in anesthetized rats |
| title_short | Gastroduodenal resistance and neural mechanisms involved in saline flow decrease elicited by acute blood volume expansion in anesthetized rats |
| title_sort | gastroduodenal resistance and neural mechanisms involved in saline flow decrease elicited by acute blood volume expansion in anesthetized rats |
| topic | blood volume expansion gastroduodenal resistance duodenum pylorus !-- $MVD$:face("Symbol") --<FONT FACE=Symbol>a</font>-blockers vagotomy |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1997001000019 |
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