Effect of hyperoxemia and ritanserin on skeletal muscle microflow

Abstract

Serotonin2 (5-HT2) receptor antagonists (ketanserin, ritanserin) can normalize a hyperoxemia-induced disturbance in skeletal muscle oxygenation, presumably by local microflow changes. The purpose of this study was to develop equipment for local hydrogen clearance measurements with a modified eight-channel platinum electrode to assess changes in local skeletal muscle capillary blood flow induced by hyperoxemia and ritanserin (0.035 mg/kg) during hyperoxemia. Laser-Doppler flowmetry was used for regional microflow measurements. Two groups of six anesthetized and artificially ventilated rabbits were studied: group I with normoxemia and hyperoxemia [arterial PO2 (PaO2) 48 kPa; 360 Torr] and group II before and after ritanserin with hyperoxemia (PaO2 46 kPa; 345 Torr). In group I, hyperoxemia induced a mean local hydrogen clearance decrease of 22% while laser-Doppler flowmetry signal decreased 31%. In group II, ritanserin induced a 125% mean local hydrogen clearance increase compared with hyperoxemia (or 37% compared with group I normoxemia); laser-Doppler flowmetry signal increased 30%. The sum distribution of local hydrogen clearances shifted to the left during hyperoxemia and to the right after ritanserin. The conclusion from this study is that local and regional microflow changes can explain the effects of hyperoxemia and ritanserin on skeletal muscle oxygenation.

The role of regional cerebral oxygen saturation on adjustment of fraction of inspired oxygen during coronary artery bypass graft surgery

“…[1,5,7] Moreover, in several investigations in which tissue oxygenation was studied, decreased oxygenation, sometimes even to hypoxic levels, together with signs of maldistribution of capillary flow were found as a response to hyperoxemia. [5,[11][12][13] Another deleterious effect of hyperoxemia was reported by Pizov et al [4] in which they determined there was a larger increase of proinflammatory cytokines in patients treated with 100% oxygen compared with the 50% oxygen group. A delayed recovery in patients treated with 100% oxygen was reported in our study.…”

Influence of Pentobarbital, Propofol and Ketamine on Skeletal Muscle Capillary Perf usion during Hemorrhage: A Comparative Study in the Rabbit

“…Each LHC wire has a catchment volume radius of 32 pm and thus the sampling resolution is one or two capillaries in skeletal muscle [19], Since the majority of surface vessels in striated muscle are capil laries. the electrode measures mostly flow in capillaries.…”

“…the electrode measures mostly flow in capillaries. With an intercapillary' distance of 52 pm [19] and average distance between each measurement channel of 200 pm [22], chances are that each wire is placed over an independent microvascular unit [23], The sam pling volume of LDF is not known, but it is proposed to be one cubic millimeter. Consequently, the measuring volume of the Clark-type surface microelectrode is approximately 1,000 times smaller than that of LDF, and thus there is a difference in the sampling compart ments between the flow methods.…”

“…The method has been described in detail elsewhere [17][18][19]. Briefly, this technique uses an eight-channel Clark-type microelec trode (Mehrdracht Oberflachcnelektrodc.…”

Serotonin – One Possible Link between Oxygen Metabolism and the Regulation of Blood Flow in the Brain?

“…Furthermore, we have chosen not to have a control group (saline) to the ritanserin period, as it has been shown that the disturbed oxygenation is maintained even after prolonged hyperoxemia [4,8], This excludes that the normalization of P,0;> by the ritanserin injection is a time effect. In addition, in another preparation we have found that ritanserin administration (with a similar dose) during normoxemia did not affect the tissue capil lary perfusion or oxygenation [unpubl.…”