Cholecystokinin as a regulator of cardiac function and postprandial gastrointestinal blood flow in rainbow trout (Oncorhynchus mykiss)

2010 ◽  
Vol 298 (5) ◽  
pp. R1240-R1248 ◽  
Author(s):  
Henrik Seth ◽  
Albin Gräns ◽  
Michael Axelsson
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Direct Effect ◽  
Flow Profile ◽  
Subsequent Increase ◽  
Physiological Concentration ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Gastrointestinal Blood Flow

We have studied the potential role of CCK as a regulator/modulator of the postprandial increase in gastrointestinal blood flow. Rainbow trout ( Oncorhynchus mykiss ) were instrumented with pulsed Doppler flow probes to measure the effects of CCK on cardiac output and gastrointestinal blood flow. Furthermore, vascular preparations were used to study the direct effects of CCK on the vessels. In addition, we used in situ perfused hearts to further study the effects of CCK on the cardiovascular system. When the sulfated form of CCK-8 was injected at a physiological concentration (0.19 pmol/kg) in vivo, there was a significant increase in the gastrointestinal blood flow (18 ± 4%). This increase in gastrointestinal blood flow was followed by a subsequent increase in cardiac output (30 ± 6%). When the dose was increased to 0.76 pmol/kg, there was only a 14 ± 6% increase in gastrointestinal blood flow; possibly due to a dose-dependent increase in the gill vascular resistance as previously reported or a direct effect on the heart. Nevertheless, CCK did not affect the isolated vessel preparations, and thus, it seems unlikely that CCK has a direct effect on the blood vessels of the second or third order. CCK did, however, have profound effects on the dynamics of the heart, and without a change in cardiac output, there was a significant increase in the amplitude (59 ± 4%) and rate (dQ/d t: 55 ± 4%; -dQ/d t: 208 ± 49%) of the phasic flow profile. If and how this might be coupled to a postprandial gastrointestinal hyperemia remains to be determined. We conclude that CCK has the potential as a regulator of the postprandial gastrointestinal blood flow in fish and most likely has its effect by inducing a gastrointestinal hyperemia. The mechanism by which CCK acts is at present unknown.

Nutrient-induced gastrointestinal hyperemia and specific dynamic action in rainbow trout (Oncorhynchus mykiss)—importance of proteins and lipids

2009 ◽  
Vol 296 (2) ◽  
pp. R345-R352 ◽  
Author(s):  
Henrik Seth ◽  
Erik Sandblom ◽  
Michael Axelsson
Keyword(s):  
Blood Flow ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
High Protein Diet ◽  
Specific Dynamic Action ◽  
Protein Diet ◽  
Balanced Diet ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
High Lipid ◽  
High Lipid Diet

Mechanical gastric distension induces a dorsal aortic pressor response in rainbow trout ( Oncorhynchus mykiss) with no change in gastrointestinal blood flow. To elucidate what role chemical stimuli from the digested food has on the postprandial cardiovascular response, a new method was developed to investigate the contribution of individual nutrient components. Three predigested experimental diets were injected directly into the proximal intestine of rainbow trout and cardiac output (CO), gut blood flow (Qcma), heart rate (HR), and stroke volume (SV) were recorded. Specific dynamic action (SDA) was estimated by measuring oxygen consumption. When a balanced diet (50% protein, 25% fat, 15% carbohydrate) was injected, Qcma and CO increased within 1 h by 45 and 27%, respectively. The response to a high-protein diet (70% protein, 5% fat, 15% carbohydrate) was quantitatively similar but delayed, with a maximal blood flow response after 2 h. With a high-lipid diet (60% fat, 15% protein, 15% carbohydrate), the peak increase in Qcma by 22% occurred after 30 min and thereafter declined rapidly. The SDA response (19%) to the balanced diet was temporally matched with the hyperemia. With a high-protein diet, the response is delayed and enlarged (34%) compared with the balanced diet. The high-lipid diet gave no significant SDA response. We conclude that the chemical composition of the food influences the postprandial hyperemia and the SDA, such that the components appear to work in a synergistic fashion. The present results also demonstrate that both redistribution of blood flow and an overall increase in CO contribute to the postprandial increase in gut blood flow in this species.

Effects of gastric distension on the cardiovascular system in rainbow trout (Oncorhynchus mykiss)

2008 ◽  
Vol 294 (5) ◽  
pp. R1648-R1656 ◽  
Author(s):  
Henrik Seth ◽  
Erik Sandblom ◽  
Susanne Holmgren ◽  
Michael Axelsson
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Rainbow Trout ◽  
Gastrointestinal Tract ◽  
Arterial Pressure ◽  
Oncorhynchus Mykiss ◽  
Vascular Resistance ◽  
Stomach Wall ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Chemical Stimuli

When animals feed, blood flow to the gastrointestinal tract increases to ensure an adequate oxygen supply to the gastrointestinal tissue and an effective absorption of nutrients. In mammals, this increase depends on the chemical properties of the food, as well as, to some extent, on the mechanical distension of the stomach wall. By using an inflatable nitrile balloon positioned in the stomach, we investigated the cardiovascular responses to mechanical stretch of the stomach wall in rainbow trout ( Oncorhynchus mykiss). Distension with a volume equivalent to a meal of 2% of the body mass increased dorsal aortic blood pressure by up to 29%, and central venous blood pressure increased transiently nearly fivefold. The increase in arterial pressure was mediated by an increased vascular resistance of both the systemic and the intestinal circulation. Cardiac output, heart rate, and stroke volume (SV) did not change, and only transient changes in gut blood flow were observed. The increase in arterial pressure was abolished by the α-adrenergic antagonist prazosin, indicating an active adrenergic vasoconstriction, whereas the venous pressor response could be the consequence of a passive increase in intraperitoneal pressure. Our results show that mechanical distension of the stomach causes an instantaneous increase in general vascular resistance, which may facilitate a redistribution of blood to the gastrointestinal tract when chemical stimuli from a meal induce vasodilation in the gut circulation. The normal postprandial increase in gut blood flow in teleosts is, therefore, most likely partly dependent on mechanical stimuli, as well as on chemical stimuli.

Venous hemodynamic responses to acute temperature increase in the rainbow trout (Oncorhynchus mykiss)

2007 ◽  
Vol 292 (6) ◽  
pp. R2292-R2298 ◽  
Author(s):  
Erik Sandblom ◽  
Michael Axelsson
Keyword(s):  
Cardiac Output ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Temperature Increase ◽  
Venous Return ◽  
Filling Pressure ◽  
Venous Capacitance ◽  
Cardiac Filling Pressure ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Cardiac Filling

Many ectotherms regularly experience considerable short-term variations in environmental temperature, which affects their body temperature. Here we investigate the cardiovascular responses to a stepwise acute temperature increase from 10 to 13 and 16°C in rainbow trout ( Oncorhynchus mykiss). Cardiac output increased by 20 and 31% at 13 and 16°C, respectively. This increase was entirely mediated by an increased heart rate (fH), whereas stroke volume (SV) decreased significantly by 20% at 16°C. The mean circulatory filling pressure (MCFP), a measure of venous capacitance, increased with temperature. Central venous pressure (Pven) did not change, whereas the pressure gradient for venous return (MCFP-Pven) was significantly increased at both 13 and 16°C. Blood volume, as measured by the dilution of 51Cr-labeled red blood cells, was temperature insensitive in both intact and splenectomized trout. This study demonstrates that venous capacitance in trout decreases, but cardiac filling pressure as estimated by Pven does not change when cardiac output increases during an acute temperature increase. SV was compromised as fH increased with temperature. The decreased capacitance likely serves to prevent passive pooling of blood in the venous periphery and to maintain cardiac filling pressure and a favorable pressure gradient for venous return.

scholarly journals INFLUENCE OF HYPOXIA AND ADRENALINE ADMINISTRATION ON CORONARY BLOOD FLOW AND CARDIAC PERFORMANCE IN SEAWATER RAINBOW TROUT (ONCORHYNCHUS MYKISS)

1994 ◽  
Vol 193 (1) ◽  
pp. 209-232 ◽  
Author(s):  
A Gamperl ◽  
A Pinder ◽  
R Grant ◽  
R Boutilier
Keyword(s):  
Blood Flow ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Coronary Blood Flow ◽  
Cardiac Performance ◽  
Hypoxic Exposure ◽  
Coronary Perfusion ◽  
Adrenergic Stimulation ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Cardiovascular Performance

To investigate the relationship between cardiac performance and coronary perfusion, cardiovascular variables (Q(dot), Vs, fh, Pda) and coronary blood flow (q·cor) were measured in rainbow trout (Oncorhynchus mykiss) (1.2­1.6 kg) before and after adrenergic stimulation (1.0 µg kg-1 adrenaline) under conditions of (1) normoxia, (2) hypoxia (approximate PwO2 12 kPa) and (3) 2.5 h after returning to normoxia. q·cor for resting fish under normoxic conditions was 0.14±0.02 ml min-1 kg-1 (approximately 0.85 % of Q(dot)). When exposed to hypoxia, although both resting Q(dot) and q·cor increased, q·cor increased to a greater degree (Q(dot) by 17 % and q·cor by 36 %). During hypoxia, maximum adrenaline-stimulated Q(dot) was comparable to that observed for normoxic fish. However, because Q(dot) was elevated in resting hypoxic fish, the capacity of hypoxic fish to increase Q(dot) above resting levels was 50 % lower than that measured in normoxic fish. Although maximum q·cor in adrenaline-injected hypoxic trout was greater than that measured in normoxic trout, post-injection increases in q·cor (above resting levels) were not different between the two groups. Two and a half hours after hypoxic exposure, resting Q(dot) was still elevated (11 %) above normoxic levels, and the ability to increase Q(dot) when adrenergically stimulated was not fully restored. These results suggest (1) that resting q·cor in salmonids is approximately 1 % of Q(dot), (2) that increases in q·cor may be important in maintaining cardiovascular performance during hypoxic conditions, (3) that interactions between alpha-adrenergic constriction and metabolically related vasodilation of the coronary vasculature are important in determining q·cor in fish, (4) that exposure of fish to moderate environmental hypoxia reduces the scope for adrenergically mediated increases in Q(dot), and (5) that periods of recovery in excess of several hours are required before cardiovascular performance returns to pre-hypoxic levels.

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