Local cerebral blood flow response to locally infused 2-chloroadenosine during hypotension in piglets

Park, T.S.; Gidday, Jeffrey M.; Gonzales, Ernesto R.

doi:10.1016/0165-3806(91)90115-y

Cited by 8 publications

(4 citation statements)

References 24 publications

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“…Using this technique in the present study, we observed a 142% increase in cor tical CBF in response to probe perfusion with 10 -5 M 2-CADO, consistent with our previous study (Park et al, 1991). It is expected that the actual concentration of 2-CADO achieved in the intersti tium surrounding the vascular smooth muscle cells is likely to be lower than 10 -5 M, as discussed pre viously (Park et al, 1991). The observed increase in piglet parenchymal CBF was similar to the 131 % increase in rat caudate nucleus CBF noted by Van Wylen et al (1989) using the same microdialysis hydrogen clearance technique and the same 2-CADO concentration.…”

Section: Discussionsupporting

confidence: 81%

“…Recent studies have demonstrated the utility of delivering adenosine and other drugs directly to the parenchymal tissue via microdialysis probes, which can also be modified with implanted platinum elec trodes to measure the resultant changes in local CBF by H2 clearance Park et al, 1991). Using this technique in the present study, we observed a 142% increase in cor tical CBF in response to probe perfusion with 10 -5 M 2-CADO, consistent with our previous study (Park et al, 1991).…”

Section: Discussionsupporting

confidence: 80%

Section: Discussionsupporting

confidence: 79%

“…Physical/hemodynamic factors discussed previ ously (Wei et al, 1980) may underlie this observa tion; perhaps longitudinal differences in adenosine receptor complement and/or sensitivity of the smooth muscle transduction processes to adenosine also contribute. In any case, the demonstrated va sodilative response to 2-CADO indicates that aden osine receptors are present on the pial resistance vessels of the newborn pig and extends to the pial microcirculation the general hypothesis put forth by us (Park et al, 1987) and subsequently supported by other studies (Park et al, , 1991Laudignon et al, 1990;Park and Gidday, 1990) that endogenous adenosine participates in the regulation of newborn CBF.…”

Section: Discussionmentioning

confidence: 54%

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Effect of 2-Chloroadenosine on Cerebrovascular Reactivity to Hypercapnia in Newborn Pig

Gidday

Park

1992

J Cereb Blood Flow Metab

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Summary:The effect of local administration of vasodila tive concentrations of the adenosine receptor agonist 2-chloroadenosine (2-CADO) on the hyperemic responses of the pial and parenchymal microcirculations to graded hypercapnia was determined. The cranial window and brain microdialysis-hydrogen clearance techniques were utilized in two groups of isoflurane-anesthetized newborn pigs to measure changes in pial diameters and local CBF, respectively, in response to graded hypercapnia in the absence and presence of 2-CADO. Progressive size dependent dilations of pial arterioles [small = 41 ± 7 !-Lm (mean ± SD), intermediate = 78 ± 13 !-Lm, and large = 176 ± 57 !-Lm in diameter 1 occurred in response to graded hypercapnia alone (P aco2 = 58 and 98 mm Hg) and to superfusions of 2-CADO 00-5 M) during normocapnia; the magnitude of the dilative response to each of these The mechanism underlying hypercapnic hyper emia in brain is not well understood. A hypercap nia-induced increase in extracellular hydrogen ion concentration is likely to be the initial step of this process (Kontos et aI., 1977), but hydrogen ion may not be the final effector. There is evidence that the hyperemia in newborn animals results from hydro gen ion-stimulated production of vasodilative pros tanoids (Wagerle and Mishra, 1988; Leffler et aI., 1989). The purine metabolite adenosine has also been hypothesized to participate in the mediation of hypercapnic vasodilation, based on studies in which adenosine receptor blockade reduced hypercapnia- Abbreviations used: ANOYA, analysis of variance; 2-CADO, 2-chloroadenosine. 656stimuli was inversely proportional to vessel size. When hypercapnia was induced concomitantly with 2-CADO superfusion, the dilative effects of each stimulus were directly additive. Similarly, local microdialysis infusion of 10-5 M 2-CADO, which doubled CBF during normo capnia, did not affect the hyperemic response of the pa renchymal circulation to graded hypercapnia (P aco2 = 69 and 101 mm Hg). Our findings are consistent with the participation of adenosine in the mediation of cerebral hypercapnic hyperemia. If, however, adenosine is not in volved in this dilative response, our results indicate that concomitant vascular and neuromodulatory actions in duced by adenosine receptor stimulation do not affect the mechanism responsible for the hypercapnic hyperemic response.

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Section: Discussionsupporting

confidence: 81%

Section: Discussionsupporting

confidence: 80%