Figure 3
Epinephrine stimulates activation of SS, but not normal, RBC adhesion to vessel walls in nude mice. (A-D) Microscopic observations of postcapillary venules were conducted through implanted window chambers after infusion of RBCs into the tail vein of nude mice using × 5 and × 20 magnification to observe human RBCs and × 20 magnification to observe murine RBCs. Vessels without adherent cells appear gray due to rapidly moving fluorescent RBCs. (A) Infusion of sham-treated (n = 8), forskolin (fsk) + IBMX–treated (n = 3) or epi-treated (n = 8) human SS RBCs. Sham-treated human SS RBCs showed little adhesion to vessel walls, whereas fsk + IBMX–treated and, to a greater extent, epi-treated human SS RBCs showed marked adhesion to postcapillary venules, with intermittent vaso-occlusion, as indicated by arrows. (B) Infusion of sham-treated (n = 3) or epi-treated (n = 3) normal human RBCs. Sham-treated human normal RBCs showed no adhesion to venule walls. Epi had little to no effect on human normal RBC adhesion to vessel walls. Scale bar = 200 μm. (C) Infusion of sham-treated (n = 4) or epi-treated (n = 4) murine sickle cells. Sham-treated murine SS RBCs showed very weak adhesion to vessel walls. Epi increased adhesion of murine SS RBCs to postcapillary venules. (D) Infusion of sham-treated (n = 3) or epi-treated (n = 3) normal murine RBCs. Sham- or epi-treated normal murine RBCs showed no adhesion to venule walls. (E) Fsk + IBMX or epi enhances human SS RBC occupation of venular length. SS RBCs were sham treated, IBMX + fsk treated, or epi treated (n = 3 for each treatment) prior to infusion into the tail vein of nude mice. The values of 30 segments of vessels analyzed were averaged among groups of animals to represent the mean percent venular length occupied by SS RBCs. Error bars show SEM of 3 different experiments for each treatment. *P < .05 compared with sham-treated regardless of the vessel diameter within the ranges specified. (F) Percentage venular length occupied by human SS RBCs related to venular diameter. Animals were injected with sham- (■) or epi-treated (▴) SS RBCs. Error bars show SEM for 6 different experiments for each treatment. *P < .001 compared with sham-treated. Data were compared using 1-way ANOVA analysis followed by Bonferroni corrections for multiple comparisons.

Epinephrine stimulates activation of SS, but not normal, RBC adhesion to vessel walls in nude mice. (A-D) Microscopic observations of postcapillary venules were conducted through implanted window chambers after infusion of RBCs into the tail vein of nude mice using × 5 and × 20 magnification to observe human RBCs and × 20 magnification to observe murine RBCs. Vessels without adherent cells appear gray due to rapidly moving fluorescent RBCs. (A) Infusion of sham-treated (n = 8), forskolin (fsk) + IBMX–treated (n = 3) or epi-treated (n = 8) human SS RBCs. Sham-treated human SS RBCs showed little adhesion to vessel walls, whereas fsk + IBMX–treated and, to a greater extent, epi-treated human SS RBCs showed marked adhesion to postcapillary venules, with intermittent vaso-occlusion, as indicated by arrows. (B) Infusion of sham-treated (n = 3) or epi-treated (n = 3) normal human RBCs. Sham-treated human normal RBCs showed no adhesion to venule walls. Epi had little to no effect on human normal RBC adhesion to vessel walls. Scale bar = 200 μm. (C) Infusion of sham-treated (n = 4) or epi-treated (n = 4) murine sickle cells. Sham-treated murine SS RBCs showed very weak adhesion to vessel walls. Epi increased adhesion of murine SS RBCs to postcapillary venules. (D) Infusion of sham-treated (n = 3) or epi-treated (n = 3) normal murine RBCs. Sham- or epi-treated normal murine RBCs showed no adhesion to venule walls. (E) Fsk + IBMX or epi enhances human SS RBC occupation of venular length. SS RBCs were sham treated, IBMX + fsk treated, or epi treated (n = 3 for each treatment) prior to infusion into the tail vein of nude mice. The values of 30 segments of vessels analyzed were averaged among groups of animals to represent the mean percent venular length occupied by SS RBCs. Error bars show SEM of 3 different experiments for each treatment. *P < .05 compared with sham-treated regardless of the vessel diameter within the ranges specified. (F) Percentage venular length occupied by human SS RBCs related to venular diameter. Animals were injected with sham- (■) or epi-treated (▴) SS RBCs. Error bars show SEM for 6 different experiments for each treatment. *P < .001 compared with sham-treated. Data were compared using 1-way ANOVA analysis followed by Bonferroni corrections for multiple comparisons.

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