Assuntos
Velocidade do Fluxo Sanguíneo , Intestino Delgado/transplante , Isquemia , Leucócitos/fisiologia , Veias Mesentéricas/fisiopatologia , Traumatismo por Reperfusão/fisiopatologia , Vênulas/fisiologia , Animais , Intestino Delgado/patologia , Intestino Delgado/fisiologia , Masculino , Veias Mesentéricas/patologia , Microcirculação/patologia , Microcirculação/fisiologia , Microcirculação/fisiopatologia , Ratos , Ratos Wistar , Fluxo Sanguíneo Regional , Traumatismo por Reperfusão/patologia , Vênulas/patologiaRESUMO
The influence of changes in pCO2, pH and pO2 on the aggregation of rabbit blood platelets was studied in vitro, with emphasis on hypercapnia, acidosis and hypoxia. Hypercapnia combined with acidosis caused a reduction in rabbit platelet aggregation, as induced by collagen, thrombin and ADP; the effect being most pronounced with collagen and smallest with ADP. Hypoxia reduced thrombin induced platelet aggregation, but had no effect on ADP and collagen induced aggregation. Synergistic activation of rabbit platelets, as induced by the addition of serotonin to platelet rich plasma together with collagen or ADP, seemed to be equally sensitive to changes in pCO2 and pH as activation by the individual agents, and insensitive to changes in pO2.
Assuntos
Hipóxia Celular , Hipercapnia/metabolismo , Agregação Plaquetária , Difosfato de Adenosina/farmacologia , Animais , Dióxido de Carbono/farmacologia , Colágeno/farmacologia , Concentração de Íons de Hidrogênio , Oxigênio/farmacologia , Pressão Parcial , Agregação Plaquetária/efeitos dos fármacos , Coelhos , Trombina/farmacologiaRESUMO
Changes in the vasomotion waveform were studied in transverse arterioles (TAs) and their first-order side branches (FOSs) in the tenuissimus muscle of 14 young, anesthetized rabbits during stepwise arterial pressure reduction and local application of adenosine using intravital video microscopy. Pressure reduction resulted in a systematic increase in vasomotion cycle length (CL) and amplitude (A) concomitant with an increase in effective vascular diameter (Deff) and maximum diameter and a decrease in blood flow (Q). During adenosine application Deff and maximum diameter also increased, but CL and A did not change systematically. At moderate pressure reductions and during adenosine application CL changes were limited (less than 1.5 s) and nonsystematic, agreeing with an earlier study (D. W. Slaaf, G. J. Tangelder, H. C. Teirlinck, and R. S. Reneman. Microvasc. Res. 33: 71-80, 1987). In TAs these changes resulted from changes in both the dilation and the constriction phase. In FOSs, however, changes in CL were caused by prolongation of the dilation phase alone. At greatly reduced pressure levels, the CL increase was more pronounced and in both TAs and FOSs was caused by plateau formation in the dilation phase. Stretch of the arteriolar wall does not seem to play a role in control of the vasomotion waveform. Because the onsets of dilation always occur synchronously in TAs and FOSs, but the onsets of constriction do not, vasomotion seems to be a series of rhythmic dilations.
