Summary
Urethane-anesthetized thoracotomized rats were used to ascertain whether the density of plasma-perfused capillaries increases in the heart during pharmacologically induced vasodilation. Carbocromene, in a dose of 3.0 mg/(kg×min) i.v., infused for 5 min, raised coronary blood flow from 6.2±0.6 to 15.6±0.1 ml/(min×g); heart rate and blood pressure were only slightly changed. Capillary density was determined by timed infusions of a plasma label (FITC or RB 200 coupled with γ-globulin), infused for different periods of time in the same animal. No significant difference could be observed in the number of capillaries marked for 10 min in the carbocromene-treated rats as compared to the controls (carbocromene-treated rats: 3,630±90 cap/mm2 subepicardium, 3,360±70 cap/mm2 subendocardium; controls: 3,750±140 cap/mm2 subepicardium, 3,210±90 cap/mm2 subendocardium). In those rats treated with the vasodilator the filling of the microcirculatory system was nearly complete within a labelling period of 1 sec (3,500±170 cap/mm2 subepicardium, 3,070±110 cap/mm2 subendocardium), whereas significantly lower values were found when the dye was infused for 1 sec in the controls (2,560±460 cap/mm2 subepicardium, 1,960±400 cap/mm2 subendocardium). The results indicate that the filling of the cardiac microcirculatory system is accelerated by a pharmacologically induced vasodilation, the maximal density of plasma-perfused capillaries is not raised, however.
Zusammenfassung
In Urethan-narkotisierten, thorakotomierten Ratten wurde untersucht, ob die Dichte plasmaperfundierter Kapillaren im Herzen unter einer pharmakologisch ausgelösten Vasodilatation ansteigt. Carbocromen führte in einer Dosis von 3,0 mg/(kg×min) i.v., über 5 min infundiert, zu einem Anstieg der Koronardurchblutung von 6,2±0,6 auf 15,6±0,1 ml/(min×g); Herzfrequenz und Blutdruck waren hierbei nur geringfügig verändert. Die Kapillardichte wurde bestimmt, indem ein plasmamarkierender Farbstoff (FITC bzw. RB 200 an γ-Globulin gekoppelt) für unterschiedlich lange Zeiten demselben Versuchstier infundiert wurde. Bei einer Farbstoff-Applikationszeit von 10 min ergaben sich keine signifikanten Unterschiede in der Kapillardichte Carbocromen-behandelter Tiere im Vergleich zu den Kontrollen (Carbocromen-behandelte Ratten: 3630±90 Kap./mm2 Subepikard. 3360±70 Kap./mm2 Subendokard; Kontrolle: 3750±140 Kap./mm2 Subepikard, 3210±90 Kap./mm2 Subendokard). In den mit dem Vasodilatator behandelten Tieren fand sich bereits nach 1 s eine nahezu vollständige Markierung des Kapillarsystems (3500±170 Kap./mm2 Subepikard, 3070±110 Kap./mm2 Subendokard), während signifikant niedrigere Werte bei einer entsprechenden Markierungszeit in den Kontrollversuchen beobachtet wurden (2560±460 Kap./mm2 Subepikard, 1960±400 Kap./mm2 Subendokard). Die Ergebnisse zeigen, daß die Füllung der kardialen Mikrozirkulation unter der pharmakologisch ausgelösten Vasodilatation beschleunigt erfolgt, daß aber die maximale Dichte plasmadurchströmter Kapillaren nicht ansteigt.
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This research project was supported by the “Deutsche Forschungsgemeinschaft, SFB 89, Kardiologie, Göttingen”. Part of this study was presented at the 22nd meeting of the Deutsche Pharmakologische Gesellschaft in Mainz 1981 (36).
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Schubothe, M., Vetterlein, F. & Schmidt, G. Density of plasma-perfused capillaries in the rat heart during carbocromene-induced vasodilation. Basic Res Cardiol 78, 113–123 (1983). https://doi.org/10.1007/BF01906665
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DOI: https://doi.org/10.1007/BF01906665