Gastrointestinal Blood Flow

Vowinkel, Thorsten; Granger, D. Neil

doi:10.1002/9781118512074.ch11

Cited by 2 publications

(7 citation statements)

References 172 publications

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“…Current consensus holds that the regulated variable in the myogenic response is vessel wall tension (166,171,280,514) (Fig. 3).…”

Section: Intrinsic Vasoregulationmentioning

confidence: 99%

“…Arteriolar tone controls blood flow (and O 2 delivery to capillaries), while precapillary sphincter tone controls the number of perfused capillaries (and, thereby, O 2 delivery to cells). There are two interrelated mechanisms by which alterations in metabolic activity are "sensed" and subsequently elicit adjustments in microvascular tone: (i) tissue pO 2 and (ii) vasoactive end-products of aerobic metabolism (166,178,280,281,514) (Fig. 4).…”

Section: Intrinsic Vasoregulationmentioning

confidence: 99%

“…Vasoactive by-products of metabolism can provide an indirect link between metabolic activity and microvascular tone (166,171,280,441,514). In this scenario, an increase in oxidative metabolism results in the generation of vasodilator metabolites (e.g., adenosine, osmolality, and H + ) and the accumulation of these metabolites in the perivascular space should decrease the tone of (i) arterioles, resulting in an increased blood flow and capillary hydrostatic pressure and (ii) precapillary sphincters, resulting in an increased capillary surface/exchange area.…”

Section: Intrinsic Vasoregulationmentioning

confidence: 99%

“…There is also some evidence implicating nitric oxide (NO) in the regulation of GI blood flow (280,281,514). Studies employing inhibitors of nitric oxide synthase (eNOS) suggest that endothelial cell-derived NO contributes to the maintenance of vascular tone in the stomach (389) and intestine (48).…”

Section: Intrinsic Vasoregulationmentioning

confidence: 99%

“…6). Oxygen uptake remains relatively constant over a wide range of blood flows as a result of reciprocal changes in capillary density; decreases in flow result in increases in capillary density and vice versa (166,280,292,440,514). Oxygen uptake is only affected by severe reductions in blood flow; at which point oxygen uptake becomes flow-dependent.…”

Section: Intrinsic Vasoregulationmentioning

confidence: 99%

See 4 more Smart Citations

The Gastrointestinal Circulation: Physiology and Pathophysiology

Granger

Holm

Kvietys

2015

Comprehensive Physiology

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The gastrointestinal (GI) circulation receives a large fraction of cardiac output and this increases following ingestion of a meal. While blood flow regulation is not the intense phenomenon noted in other vascular beds, the combined responses of blood flow, and capillary oxygen exchange help ensure a level of tissue oxygenation that is commensurate with organ metabolism and function. This is evidenced in the vascular responses of the stomach to increased acid production and in intestine during periods of enhanced nutrient absorption. Complimenting the metabolic vasoregulation is a strong myogenic response that contributes to basal vascular tone and to the responses elicited by changes in intravascular pressure. The GI circulation also contributes to a mucosal defense mechanism that protects against excessive damage to the epithelial lining following ingestion of toxins and/or noxious agents. Profound reductions in GI blood flow are evidenced in certain physiological (strenuous exercise) and pathological (hemorrhage) conditions, while some disease states (e.g., chronic portal hypertension) are associated with a hyperdynamic circulation. The sacrificial nature of GI blood flow is essential for ensuring adequate perfusion of vital organs during periods of whole body stress. The restoration of blood flow (reperfusion) to GI organs following ischemia elicits an exaggerated tissue injury response that reflects the potential of this organ system to generate reactive oxygen species and to mount an inflammatory response. Human and animal studies of inflammatory bowel disease have also revealed a contribution of the vasculature to the initiation and perpetuation of the tissue inflammation and associated injury response.

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“…Current consensus holds that the regulated variable in the myogenic response is vessel wall tension (166,171,280,514) (Fig. 3).…”

Section: Intrinsic Vasoregulationmentioning

confidence: 99%