Håkan Björne
Karolinska Institutet
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Publication
Featured researches published by Håkan Björne.
Journal of Clinical Investigation | 2004
Håkan Björne; Joel Petersson; Mia Phillipson; Eddie Weitzberg; Lena Holm; Jon O. Lundberg
Salivary nitrate from dietary or endogenous sources is reduced to nitrite by oral bacteria. In the acidic stomach, nitrite is further reduced to NO and related compounds, which have potential biological activity. We used an in vivo rat model as a bioassay to test effects of human saliva on gastric mucosal blood flow and mucus thickness. Gastric mucosal blood flow and mucus thickness were measured after topical administration of human saliva in HCl. The saliva was collected either after fasting (low in nitrite) or after ingestion of sodium nitrate (high in nitrite). In additional experiments, saliva was exchanged for sodium nitrite at different doses. Mucosal blood flow was increased after luminal application of nitrite-rich saliva, whereas fasting saliva had no effects. Also, mucus thickness increased in response to nitrite-rich saliva. The effects of nitrite-rich saliva were similar to those of topically applied sodium nitrite. Nitrite-mediated effects were associated with generation of NO and S-nitrosothiols. In addition, pretreatment with an inhibitor of guanylyl cyclase markedly inhibited nitrite-mediated effects on blood flow. We conclude that nitrite-containing human saliva given luminally increases gastric mucosal blood flow and mucus thickness in the rat. These effects are likely mediated through nonenzymatic generation of NO via activation of guanylyl cyclase. This supports a gastroprotective role of salivary nitrate/nitrite.
Shock | 2002
Rickard E. Malmström; Håkan Björne; Anders Oldner; Mikael Wanecek; Marie Fredriksson; Jon O. Lundberg; Eddie Weitzberg
The gut is considered a central organ in the pathogenesis of sepsis and multiple organ failure, where several mediators, including endothelin (ET) and nitric oxide (NO), are involved. The aim of the current study was to characterize, by direct measurements, the intestinal NO production in the anesthetized pig during normal and endotoxemic conditions. In pigs subjected to endotoxin infusion, there was a progressive decrease in jejunal luminal NO levels, as well as portal venous blood flow and blood pressure. The ET-blocker 4-tert-butyl-N-[6-(2-hydroxy-ethoxy)-5-(2-methoxy-phenoxy)-2,2′-bipyrimidin-4-yl]-benzenesulfonamide (bosentan) completely reversed the reduction in portal venous blood flow without affecting intestinal NO levels. In control pigs, the NO synthase inhibitor Nω-nitro-L-arginine methyl ester dose-dependently decreased intestinal NO levels and mesenteric blood flow—effects that were reversed by L-arginine. We conclude that intestinal NO is a product of mucosal NO synthase activity, and is profoundly decreased during endotoxemia in the pig.
Acta Anaesthesiologica Scandinavica | 2015
C. Hällsjö Sander; Magnus Hallbäck; F. Suarez Sipmann; Mats Wallin; Anders Oldner; Håkan Björne
We have evaluated a new method for continuous monitoring of effective pulmonary blood flow (COEPBF), i.e. cardiac output (CO) minus intra‐pulmonary shunt, during mechanical ventilation. The method has shown good trending ability during severe hemodynamic challenges in a porcine model with intact lungs. In this study, we further evaluate the COEPBF method in a model of lung lavage.
World Journal of Gastroenterology | 2017
Richard Shore; Håkan Björne; Yoko Omoto; Anna Siemiatkowska; Jan Åke Gustafsson; Mats Lindblad; Lena Holm
AIM To evaluate sex differences and the effects of oestrogen administration in rat gastric mucosal defence. METHODS Sex differences in gastric mucus thickness and accumulation rate, absolute gastric mucosal blood flow using microspheres, the integrity of the gastric mucosal epithelium in response to a chemical irritant and the effects of oestrogen administration on relative gastric mucosal blood flow in an acute setting was assessed in an in vivo rat experimental model. Subsequently, sex differences in the distribution of oestrogen receptors and calcitonin gene related peptide in the gastric mucosa of animals exposed to oestrogen in the above experiments was evaluated using immunohistochemistry. RESULTS The absolute blood flow in the GI-tract was generally higher in males, but only significantly different in the corpus part of the stomach (1.12 ± 0.12 mL/min•g in males and 0.51 ± 0.03 mL/min•g in females) (P = 0.002). After removal of the loosely adherent mucus layer the thickness of the firmly adherent mucus layer in males and females was 79 ± 1 µm and 80 ± 3 µm respectively. After 60 min the mucus thickness increased to 113 ± 3 µm in males and 121 ± 3 µm in females with no statistically significant difference seen between the sexes. Following oestrogen administration (0.1 followed by 1 µg/kg•min), mean blood flow in the gastric mucosa decreased by 31% [68 ± 13 perfusion units (PFU)] in males which was significantly different compared to baseline (P = 0.02). In females however, mean blood flow remained largely unchanged with a 4% (5 ± 33 PFU) reduction. The permeability of the gastric mucosa increased to a higher level in females than in males (P = 0.01) after taurocholate challenge. However, the calculated mean clearance increase did not significantly differ between the sexes [0.1 ± 0.04 to 1.1 ± 0.1 mL/min•100 g in males and 0.4 ± 0.3 to 2.1 ± 0.3 mL/min•100 g in females (P = 0.065)]. There were no significant differences between 17β-Estradiol treated males (mean ratio of positive staining ± SEM) (0.06 ± 0.07) and females (0.11 ± 0.11) in the staining of ERα (P = 0.24). Also, there were no significant differences between 17β-Estradiol treated males (0.18 ± 0.21) and females (0.06 ± 0.12) in the staining of ERβ (P = 0.11). Finally, there were no significant differences between 17β-Estradiol treated males (0.04 ± 0.05) and females (0.11 ± 0.10) in the staining of CGRP (P = 0.14). CONCLUSION Gastric mucosal blood flow is higher in male than in female rats and is reduced in male rats by oestrogen administration.
Nitric Oxide | 2006
Jon O. Lundberg; Martin Feelisch; Håkan Björne; Emmelie Å. Jansson; Eddie Weitzberg
Free Radical Biology and Medicine | 2007
Emmelie Å. Jansson; Joel Petersson; Claudia Reinders; Tanja Sobko; Håkan Björne; Mia Phillipson; Eddie Weitzberg; Lena Holm; Jon O. Lundberg
Critical Care Medicine | 2005
Håkan Björne; Mirco Govoni; Daniel C. Törnberg; Jon O. Lundberg; Eddie Weitzberg
Free Radical Biology and Medicine | 2006
Håkan Björne; Eddie Weitzberg; Jon O. Lundberg
American Journal of Respiratory and Critical Care Medicine | 2003
Daniel C. Törnberg; Håkan Björne; Jon O. Lundberg; Eddie Weitzberg
Nitric Oxide | 2001
Rickard E. Malmström; Håkan Björne; Kjell Alving; Eddie Weitzberg; Jon O. Lundberg