Relative contribution of “pressure pump” and “peristaltic pump” to gastric emptying

1998 ◽  
Vol 114 ◽  
pp. A770 ◽  
Author(s):  
K. Indireshkumar ◽  
H Faas ◽  
JG Brasseur ◽  
GS Hebbard ◽  
P Kunz ◽  
...  
2000 ◽  
Vol 278 (4) ◽  
pp. G604-G616 ◽  
Author(s):  
K. Indireshkumar ◽  
James G. Brasseur ◽  
Henryk Faas ◽  
Geoffrey S. Hebbard ◽  
Patrik Kunz ◽  
...  

The relative contributions to gastric emptying from common cavity antroduodenal pressure difference (“pressure pump”) vs. propagating high-pressure waves in the distal antrum (“peristaltic pump”) were analyzed in humans by high-resolution manometry concurrently with time-resolved three-dimensional magnetic resonance imaging during intraduodenal nutrient infusion at 2 kcal/min. Gastric volume, space-time pressure, and contraction wave histories in the antropyloroduodenal region were measured in seven healthy subjects. The subjects fell into two distinct groups with an order of magnitude difference in levels of antral pressure activity. However, there was no significant difference in average rate of gastric emptying between the two groups. Antral pressure history was separated into “propagating high-pressure events” (HPE), “nonpropagating HPEs,” and “quiescent periods.” Quiescent periods dominated, and average pressure during quiescent periods remained unchanged with decreasing gastric volume, suggesting that common cavity pressure levels were maintained by increasing wall muscle tone with decreasing volume. When propagating HPEs moved to within 2–3 cm of the pylorus, pyloric resistance was found statistically to increase with decreasing distance between peristaltic waves and the pylorus. We conclude that transpyloric flow tends to be blocked when antral contraction waves are within a “zone of influence” proximal to the pylorus, suggesting physiological coordination between pyloric and antral contractile activity. We further conclude that gastric emptying of nutrient liquids is primarily through the “pressure pump” mechanism controlled by pyloric opening during periods of relative quiescence in antral contractile wave activity.


1990 ◽  
Vol 259 (6) ◽  
pp. G1025-G1030 ◽  
Author(s):  
H. C. Lin ◽  
J. E. Doty ◽  
T. J. Reedy ◽  
J. H. Meyer

Exposure of the small intestine to acid inhibits gastric emptying in a dose-related fashion that depends on titratable acidity and pH. Little information is available on the location of this inhibitory mechanism or on the relative contribution of titratable acidity and pH to this feedback control. We hypothesized that the dependence on titratable acidity is related to the length of the intestine exposed to acid and that the dependence on pH is related to the region of the intestine exposed to acid. To test these ideas, we studied 11 dogs with duodenal and jejunal fistulas. The inhibitory effects were tested when different lengths of the small intestine were exposed to test solutions of 0.03, 0.06, and 0.12 meq/ml titratable acidities. pH as an independent covariable was separated from titratable acidity by comparing the inhibition of gastric emptying of lactic acid (pH fixed to 2.4) to HCl (pH 0.96-1.6). Maximal inhibition of gastric emptying by both acids depended on acid exposure of a length of small intestine that was greater than 65 but less than or equal to 150 cm long. When acid was confined to the proximal 15 cm, increasing concentration of HCl (decreasing pH) resulted in increasing inhibition, but this effect was absent with increasing concentration of lactic acid (fixed pH). Inhibition was absent when 0.06 meq/ml HCl was infused into the intestine beyond the midintestine.(ABSTRACT TRUNCATED AT 250 WORDS)


1993 ◽  
Vol 264 (2) ◽  
pp. G261-G271 ◽  
Author(s):  
T. Haba ◽  
S. K. Sarna

We investigated the mechanisms of regulation of gastroduodenal emptying of solid meals by gastropyloroduodenal contractions in six conscious dogs. The spatial and temporal parameters of gastropyloroduodenal contractions were correlated with the rate of gastroduodenal emptying. The rate of gastroduodenal emptying exhibited a significant positive correlation with the 1) mean frequency of corporeal and antral contractions; 2) mean frequency, amplitude, duration, and area under pyloric contractions; 3) percentage of contractions that propagated in the distal duodenum, and the mean distance of their propagation; 4) percentage of contractions that propagated within the stomach, including the pylorus; 5) percentage of contractions that propagated from the antrum or the pylorus to the proximal duodenum; and 6) ratio of the mean frequency of contractions in the antrum to that in the proximal or the distal duodenum during the entire period of gastroduodenal emptying. The major factors that exhibited a significant negative correlation with gastroduodenal emptying were the total number, amplitude, duration, and area under contractions in the whole duodenum during the entire period of gastroduodenal emptying. We conclude that the antropyloroduodenal contractions, acting as a peristaltic pump, are a major factor in the regulation of gastric emptying of solid meals. The propagating contractions in the distal duodenum promote gastric emptying by rapidly removing the chyme from this area, whereas the nonpropagated contractions in the duodenum may provide a mechanical resistance to gastric emptying.


2001 ◽  
Vol 120 (5) ◽  
pp. A465-A465
Author(s):  
D PINTO ◽  
M GIOVANNAMARRA ◽  
V STANGHELLINI ◽  
M MARENGO ◽  
N MONETTI ◽  
...  

2003 ◽  
Vol 8 (4) ◽  
pp. 252-265 ◽  
Author(s):  
Manuel G. Calvo ◽  
P. Avero ◽  
M. Dolores Castillo ◽  
Juan J. Miguel-Tobal

We examined the relative contribution of specific components of multidimensional anxiety to cognitive biases in the processing of threat-related information in three experiments. Attentional bias was assessed by the emotional Stroop word color-naming task, interpretative bias by an on-line inference processing task, and explicit memory bias by sensitivity (d') and response criterion (β) from word-recognition scores. Multiple regression analyses revealed, first, that phobic anxiety and evaluative anxiety predicted selective attention to physical- and ego-threat information, respectively; cognitive anxiety predicted selective attention to both types of threat. Second, phobic anxiety predicted inhibition of inferences related to physically threatening outcomes of ambiguous situations. And, third, evaluative anxiety predicted a response bias, rather than a genuine memory bias, in the reporting of presented and nonpresented ego-threat information. Other anxiety components, such as motor and physiological anxiety, or interpersonal and daily-routines anxiety made no specific contribution to any cognitive bias. Multidimensional anxiety measures are useful for detecting content-specificity effects in cognitive biases.


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