International journal of microcirculation, clinical and experimental / sponsored by the European Society for Microcirculation
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Int J Microcirc Clin Exp · Nov 1995
Rhythmical fluctuations of the intracerebral microcirculation studied in pigs.
Rhythmic variations in blood flow have been observed in various vascular beds, including brain. We have characterized fluctuations of the microcirculation in different locations in the brain, and studied the response to changes in arterial carbon dioxide tension, arterial pressure, and cerebrospinal fluid pressure. Laser Doppler flowmetry was performed in 20 pentobarbital-anesthetized pigs. ⋯ High intracranial pressure tended to abolish preexisting oscillations. Hypercapnia always abolished preexisting oscillations. Oscillations were more frequent if the cerebral perfusion pressure was in the low range of cerebral autoregulation, occurred more often in the cerebral locations with relatively high local flow, were most likely to be localized, and therefore probably caused by local metabolic or myogenic variations.
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Int J Microcirc Clin Exp · Jul 1995
Effects of iloprost, a stable prostacyclin analog, and its combination with NW-nitro-L-arginine on early events following lipopolysaccharide injection: observations in the hamster cheek pouch microcirculation.
The effects of iloprost, a stable prostacyclin analog, and of its combination with NW-nitro-L-arginine (L-NAG) on the microcirculatory changes observed in early stages of endotoxemia were investigated in male hamsters treated with Escherichia coli lipopolysaccharide (LPS). The cheek pouch was studied in vivo by means of intravital microscopy and mean arterial and venous pressures, mean arteriolar internal diameter, spontaneous arteriolar vasomotion, microvascular blood flow, macromolecular permeability, leukocyte adhesion and mean survival time were evaluated in animals treated with LPS alone or with the combination of LPS+iloprost and LPS+iloprost+L-NAG. Intravenous injection of LPS (100 mg/kg) per se elicited a significant reduction in mean arterial blood pressure (MABP) and arteriolar blood flow. ⋯ Topical addition of iloprost (10 ng/kg/min) evoked an early increase in macromolecular permeability and a significant decrease in leukocyte adhesion compared with animals treated with topical LPS (0.7 microgram/ml/min) alone. The combination of L-NAG+iloprost (1.3 + 10 ng/ml/min) enhanced the early increase in macromolecular permeability even further, tended to increase the macromolecular permeability and evoked a smaller decrease in leukocyte adhesion than the one observed with iloprost combined with LPS. Our results, in the hamster cheek pouch microcirculation, suggest that the use of prostacyclin could be beneficial in the treatment of early changes in endotoxic shock, but L-NAG showed no benefit in this preparation.
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Int J Microcirc Clin Exp · Jan 1995
Prevalence of cyclic changes in limb volume (volumotion) of male patients with knee injury and the effects of ischemia/reperfusion due to tourniquet.
During surgery of limbs tourniquet up to a maximum of 2 h is frequently applied which may cause ischemia/reperfusion injury (IRI). During this condition the presence of vasomotion may have consequences for the perfusion and nutritive state of the tissues. We used a noninvasive plethysmographic method to investigate periodic changes in limb circumference (volumotion) in healthy male patients (n = 24) undergoing surgery for knee injury. ⋯ Preoperatively 10 out of 24 patients (42%) showed signs of volumotion on the injured leg with a periodicity ranging from 0.8 to 6.9 cycles/min, whereas none showed volumotion in the control leg (p < 0.001). In the second measurement, taken after surgery and reperfusion while peripheral sympathetic nerves were blocked, 7 out of 18 patients (39%) showed volumotion on the injured leg and 0 on the control leg (p < 0.004). 6 h after IRI, volumotion was observed in 11 out of 17 patients (65%) on the injured leg and in 1 patient (6%) on the control leg (p < 0.001). The mean volume change in the patients with volumotion on the injured leg was 0.057 +/- 0.007 ml/100 ml tissues.(ABSTRACT TRUNCATED AT 250 WORDS)