PubMed · 1440325
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I A Borisov. 1992. [Problems in kidney physiology].. https://pubmed.ncbi.nlm.nih.gov/1440325/
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Laparoscopic techniques have become a standard approach for diagnostic and therapeutic procedures in many surgical disciplines. Recent progress in endoscopic surgery is based on the integration of computer-enhanced telemanipulation systems. Because robot-assisted radical prostatectomies take up to 10 hours, the present study was performed to evaluate the effects of prolonged intraperitoneal CO2 insufflation on hemodynamics and gas exchange in 15 patients with prostate cancer. When CO2 insufflation was initiated, peak inspiratory pressure increased and reached significant values after a 1.5-hour period of intraperitoneal CO2 insufflation. With the release of CO2, peak inspiratory pressure decreased close to baseline values. A significant increase in heart rate was observed after a 4-hour period of increased intraabdominal pressure. Mean arterial blood pressure and central venous pressure remained stable during CO2 insufflation. Minute ventilation was adjusted according to repeated blood gas analyses to maintain pH, base excess (BE), bicarbonate (HCO3?), and PaCO2 within physiologic ranges. The present data show, that prolonged CO2 insufflation during totally endoscopic robot-assisted radical prostatectomy results in only minor changes in hemodynamics and acid-base status. Because of the limited experience with long-term pneumoperitoneum, we consider invasive haemodynamic monitoring and repeat blood gas analysis essential for such operations.
The mechanisms underlying acid-base transfers across the branchial epithelium of fishes have been studied for more than 70 years. These animals are able to compensate for changes to internal pH following a wide range of acid-base challenges, and the gill epithelium is the primary site of acid-base transfers to the water. This paper reviews recent molecular, immunohistochemical, and functional studies that have begun to define the protein transporters involved in the acid-base relevant ion transfers. Both Na(+)/H(+) exchange (NHE) and vacuolar-type H(+)-ATPase transport H(+) from the fish to the environment. While NHEs have been thought to carry out this function mainly in seawater-adapted animals, these proteins have now been localized to mitochondrial-rich cells in the gill epithelium of both fresh and saltwater-adapted fishes. NHEs have been found in the gill epithelium of elasmobranchs, teleosts, and an agnathan. In several species, apical isoforms (NHE2 and NHE3) appear to be up-regulated following acidosis. In freshwater teleosts, H(+)-ATPase drives H(+) excretion and is indirectly coupled to Na(+) uptake (via Na(+) channels). It has been localized to respiratory pavement cells and chloride cells of the gill epithelium. In the marine elasmobranch, both branchial NHE and H(+)-ATPase have been identified, suggesting that a combination of these mechanisms may be utilized by marine elasmobranchs for acid-base regulation. An apically located Cl(-)/HCO(3)(-) anion exchanger in chloride cells may be responsible for base excretion in fresh and seawater-adapted fishes. While only a few species have been examined to date, new molecular approaches applied to a wider range of fishes will continue to improve our understanding of the roles of the various gill membrane transport processes in acid-base balance.
Absorption of short-chain fatty acids (SCFA) and ammonia implies considerable fluxes of protons across the epithelium of the large intestine. Efficient regulation of intracellular pH (pH(i)) is therefore essential in these cells. The aim of the present study was to examine the effects of SCFA and of ammonia on pH(i), on pH(i) regulation and to characterize the mechanisms involved in pH(i) regulation in surface enterocytes of the guinea-pig caecal and colonic mucosa. Intact epithelia from the caecum and the distal colon were mounted in a microperfusion chamber. pH(i) was measured by fluorescence microscopy using 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Addition of SCFA or ammonia to the serosal side changed the enterocyte pH(i) markedly, whereby ammonia caused larger changes in pH(i) than SCFA. In contrast, addition of SCFA to the mucosal solution had no effect on pH(i) and ammonia increased pH(i) only slightly. Basolaterally located pH(i) regulation mechanisms, Na(+)-H(+) exchange and Cl(-)-HCO(3)(-) exchange, are involved mainly in returning pH(i) to normal values. It is concluded that, due to apparently lower permeability of the apical membranes, the caecal and colonic epithelium is protected against pH(i) disturbances caused by the naturally high luminal SCFA and NH(3) concentrations. The major regulation mechanisms of pH(i) are located in the basolateral membrane of the enterocytes.