Arteriovenous Shunting in the Pig

Guba, Alexander M.

doi:10.1097/00006534-198003000-00008

Cited by 32 publications

(10 citation statements)

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“…However, microspheres of 15-25 µm do indeed shunt to the venous side in the femoral circulation of dogs and sheep (22,36) but not of cats (27) or rabbits (28). Our experiments do not tell us the origin of the arteriovenous shunting but it may be in the microvasculature of skin (36)(37)(38), duramater (6), nasal mucosa (7) or retemirabile (39).…”

Section: Arteriovenous Anastomotic Flowmentioning

confidence: 57%

Ergotamine-Induced Constriction of Cranial Arteriovenous Anastomoses in Dogs Pretreated with Phentolamine and Pizotifen

Saxena¹,

Koedam²,

Heiligers³

et al. 1983

Cephalalgia

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Previous investigations from our laboratory have shown that ergotamine causes a selective vasoconstriction in the carotid vascular bed of the dog and that the drug constricts arteriovenous anastomoses (AVAs) in cats and pigs. Since ergotamine can act via alpha-adrenergic or D-serotonergic receptors in certain vascular and non-vascular tissues, we have attempted to ascertain here if these receptors mediate the constriction of AVAs. Using radioactive microspheres of 15 microns diameter we found in the dog that about 40% of the carotid arterial blood is shunted to the venous side via AVAs. Ergotamine (2-20 micrograms X kg-1, i.v.) reduced total carotid blood flow to a larger extent in the AVA part than in the extracerebral part (muscles, ears, skin and fat). The cerebral component of carotid blood did not change. These results, confirming that ergotamine decreases arteriovenous shunting, show that the drug has a more selective action on the AVAs than on the arterioles. Pretreatment with phentolamine (0.5 mg X kg-1), pizotifen (0.5 mg X kg-1) or their combination did not effectively modify the responses to ergotamine. It is concluded that the vasoconstriction of cranial AVAs (and arterioles) by ergotamine does not appear to be primarily mediated by either alpha-adrenergic or D-serotonergic receptors. However, the role of atypical serotonin receptors has yet to be determined.

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Section: Arteriovenous Anastomotic Flowmentioning

confidence: 57%

Ergotamine-Induced Constriction of Cranial Arteriovenous Anastomoses in Dogs Pretreated with Phentolamine and Pizotifen

Saxena¹,

Koedam²,

Heiligers³

et al. 1983

Cephalalgia

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“…Our experiments do not tell us the origin of the arteriovenous shunting, but it may be in the microvasculature of skin (Molyneux, 1965;Guba, 1980), duramater (Rowbotham & Little, 1965), nasal mucosa (AnggArd, 1974), tongue (Kronert, Wurster, Pierau & Pleschka, 1980) or rete-mirabele (Gillilan & Markesbery, 1963).…”

Section: Distribution Of Carotid Blood Flowmentioning

confidence: 65%

Redistribution by 5‐hydroxytryptamine of carotid arterial blood at the expense of arteriovenous anastomotic blood flow

Saxena

Verdouw

1982

The Journal of Physiology

101

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SUMMARY1. The effects of 5-hydroxytryptamine by intravenous (1, 5 and 10 ,ug kg-' min' in cats) and intracarotid (0 5 and 2 jug kg-' min' in pigs) routes were studied on the complete distribution ofcommon carotid artery blood flow, measured with radioactive microspheres (15 ,um). In addition, the amine was also infused (0-75-3 ,ug kg-' min-') into the carotid artery of cats to observe its influence on the shunting of microspheres in the jugular venous blood.2. The basal total common carotid blood flow was distributed ipsilaterally mainly to extracerebral tissues and only little blood entered the brain. As shown by the presence of microspheres in the lungs after injection into the carotid artery (52 % in cats; 82 % in pigs), a major fraction of the carotid blood by-passed the capillary bed through arteriovenous anastomoses in the head (non-nutrient fraction).3. 5-Hydroxytryptamine redistributed the blood in favour of the nutrient compartment at the expense of arteriovenous anastomotic fraction. In cats, tissue blood flow did not significantly change but, in the pig, blood flow to all tissues, particularly to skin and ears, was substantially increased despite a reduction in total carotid blood flow. This reduction was entirely due to a change in the non-nutrient fraction.4. Intracarotid infusion of 5-hydroxytryptamine in vagosympathectomized intact or spinal cats decreased the number of microspheres appearing in the jugular venous blood, again indicating a reduction in arteriovenous anastomotic flow due to a constriction of these non-nutrient vessels.5. Cyproheptadine (1 mg kg-') completely reversed the effect of 5-hydroxytryptamine on the total carotid blood flow. However, the vasoconstriction of arteriovenous anastomoses was only partially attenuated and the vasodilatatory response was either unchanged (muscle) or even enhanced (skin, ear and bones).6. It is suggested that 5-hydroxytryptamine causes vasoconstriction of the large arteries via D-receptors which are only partly involved in the constriction of arteriovenous anastomoses. A part of the vasoconstriction in these non-nutrient vessels and the vasodilatation in extracerebral tissues are mediated by atypical 5-hydroxytryptamine receptors that are yet to be fully characterized.

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“…There is a growing belief that the key to the pharmacologic augmentation of skin flap survival rests in small vessel vasodilatation and improved nutrient inflow to the flap 6–12 . These small vessels contain smooth muscle which is subject to multiple regulatory forces including neural, hormonal, local metabolic, and physical factors.…”

Section: Discussionmentioning

confidence: 99%

The Lack of Effect of Nifedipine on Failing Skin Flaps

Miller

Falcone

Nappi

et al. 1985

The Journal of Dermatologic Surgery and Oncology

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The calcium channel blocker, nifedipine, was administered to 16 pigs in randomized blinded fashion in an unsuccessful attempt to salvage failing random pattern flaps. Despite the moderate dose of drug used, nifedipine caused significant hypotension that may have countered any beneficial effect on small vessel flow. Further studies are needed before nifedipine is abandoned as a potential agent for the pharmacologic manipulation of failing skin flaps.

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Arteriovenous Shunting in the Pig

Cited by 32 publications

References 0 publications

Ergotamine-Induced Constriction of Cranial Arteriovenous Anastomoses in Dogs Pretreated with Phentolamine and Pizotifen

Ergotamine-Induced Constriction of Cranial Arteriovenous Anastomoses in Dogs Pretreated with Phentolamine and Pizotifen

Redistribution by 5‐hydroxytryptamine of carotid arterial blood at the expense of arteriovenous anastomotic blood flow

The Lack of Effect of Nifedipine on Failing Skin Flaps

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