MICROSPHERE INFUSION REVERSES VASOCONSTRICTOR-MEDIATED CHANGE IN HINDLIMB OXYGEN-UPTAKE AND ENERGY STATUS

Citation
Ma. Vincent et al., MICROSPHERE INFUSION REVERSES VASOCONSTRICTOR-MEDIATED CHANGE IN HINDLIMB OXYGEN-UPTAKE AND ENERGY STATUS, Acta Physiologica Scandinavica, 164(1), 1998, pp. 61-69
Citations number
29
Categorie Soggetti
Physiology
ISSN journal
00016772
Volume
164
Issue
1
Year of publication
1998
Pages
61 - 69
Database
ISI
SICI code
0001-6772(1998)164:1<61:MIRVCI>2.0.ZU;2-E
Abstract
The vasoconstrictors, angiotensin II (All) and serotonin (5-HT) produc e opposing metabolic effects and appear to control different flow rout es in the constant-flow perfused rat hindlimb. In the present study th e association between vascular flow route recruitment and metabolism w as assessed by selective microsphere embolism of either route. Microsp heres (MS, 11.9 +/- 0.1 mu m, mean +/- SE diameter) were injected duri ng All, 5-HT or vehicle infusions(basal conditions) and the effects on hindlimb (4.7 +/- 0.1 g muscle) oxygen uptake ((C) over dot o(2)) and indices of energy status CrP/Cr, CrP/ATP and energy charge (EC) of th e calf muscle group assessed. MS (1.5 x 10(6)) injected during vehicle , or 5-HT infusion increased (V) over dot o(2) (P < 0.05) but did not affect energy status. During All, MS decreased (V) over dot o(2). Chan ge in (V) over dot o(2) correlated positively with CrP/Cr (r = 0.68, P < 0.0001) and CrP/ATP (r = 0.51, P < 0.001) but not EC (r = 0.08, P = 0.59). MS (1.5 x 10(6)) increased pressure but did not affect the flo w rate. The metabolic changes resulting from 1.5 x 10(6) microspheres were intensified by a second injection of 1.5 x 10(6) microspheres but further injection (>3.0 x 10(6) microspheres) began to inhibit flow. It is concluded that a finite number (less than or equal to 3.0 x 10(6 )) of microspheres of 11.9 mu m diameter has opposite effects on (C) o ver dot o(2) depending on the vasoconstrictor present and that these e ffects result from the occlusion of the different vascular route acces sed by each vasoconstrictor. The data support the proposal that hindli mb metabolism can be controlled by vasoconstrictors as a result of sel ective vascular recruitment.