Atrial stretch increases the gastric tonus of anesthetized rats.
OBJECTIVE
We assessed the effects of right atrial stretch on gastric tone and neuro-humoral pathways involved in this phenomenon.


METHODS
Anesthetized male rats were submitted for monitoring of the mean arterial pressure (MAP) and central venous pressure (CVP). A balloon catheter positioned into the stomach monitored by plethysmography the gastric volume (GV). All rats were monitored for 55-min. After the first 20-min of monitoring (basal period), rats were either submitted to a 5-min interval of atrial stretch (AS) or maintained as controls. An intra-atrial balloon catheter was distended with 30, 50, or 70 microL of saline. GV and hemodynamic data were also monitored for a further 30-min. Another set of rats, either previously submitted to subdiaphragmatic vagotomy or splanchnicectomy plus celiac ganglionectomy or maintained as controls (sham), were also submitted to AS. Each subset consisted of six rats. The plasma level of the atrial natriuretic peptide (ANP) was measured in another group of rats. Data were compared by ANOVA followed by Bonferroni's test.


RESULTS
In control rats, the GV, MAP, and CVP remained at stable levels throughout the studies. In addition to increase the CVP, AS also decreased (P<0.05) the GV by 14%, 11.5%, and 16.5% in the 30, 50, and 70 microL groups, respectively. Vagotomy prevented the GV decrease. In contrast, the AS decreased (P<0.05) the GV by 21.3% in splanchnicectomized rats.


CONCLUSIONS
AS decreased the GV of rats in a volume-dependent manner, a phenomenon prevented by vagotomy but enhanced by celiac ganglionectomy.
Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Laboratório Escola Prof Luiz Capelo, Caixa Postal 3157, 60.430-270 Fortaleza, Brazil.
R C
RC
Palheta
F H
FH
Rola
G H S
GH
Lira
D A
DA
Gomes
F M
FM
Carvalho
L L K
LL
Elias
J
J
Antunes-Rodrigues
R B
RB
Oliveira
A A
AA
Santos
D000758:Anesthesia; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism; D003964:Diaphragm / Q000294:innervation / Q000502:physiology; D005728:Ganglia, Sympathetic / Q000502:physiology; D006321:Heart / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology; D008297:Male; D009129:Muscle Tonus / Q000502:physiology*; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology; D013270:Stomach / Q000502:physiology*; D014628:Vagotomy
D009320:Atrial Natriuretic Factor