Cardiac fibroblasts inhibit ß-adrenoceptor-dependent connexin43 expression in neonatal rat cardiomyocytes.

Cardiac fibroblasts play an important role in adverse cardiac remodelling. As in many cardiac diseases connexin43 (Cx43) is altered, we wanted to elucidate whether fibroblasts may influence cardiac Cx43 expression. We used four different cell culture systems of neonatal rat cardiomyocytes (CM) and fibroblasts (FB): type 1, pure CM culture; type 2, co-culture of CM/FB; type 3, pure FB culture; type 4, Transwell® system: CM/FB co-cultured but separated by a microporous membrane. Stimulation of types 1-3 cell culture models with isoprenaline significantly enhanced Cx43-protein and Cx43-mRNA expression as well as phosphorylation of ERK and translocation of AP1 and CREB only in the CM cultures; whereas, the CM/FB co-cultures and the FB cultures did not respond to isoprenaline. Similarly, if CM and FB were separated by a microporous membrane (Transwell® system) the isoprenaline-induced increase in CM Cx43 was completely suppressed, suggesting the existence of a soluble factor responsible for the suppressant effect of FB. Angiotensin II determination in types 1 and 2 cell culture supernatants revealed that the CM/FB co-cultures exhibited a significant higher angiotensin II release than the CM cultures. Furthermore, we aimed to inhibit angiotensin II signal transduction pathway: blockade of AT1 receptors or PKC inhibition restored the responsiveness of CM/FB co-cultures to isoprenaline. Moreover, external addition of angiotensin II to CM cultures also resulted in suppression of isoprenaline-stimulated Cx43 expression in an AT1-receptor- and PKC-dependent manner. Thus, our study indicates that cardiac fibroblasts inhibit ß-adrenoceptor-dependent Cx43 signalling in CM involving angiotensin II.

[The arterial haemodynamics of the liver and spleen in patients with cirrhosis of the liver (author's transl)]. / Die arterielle Hämodynamik der Leber und der Milz bei Kranken mit Leberzirrhose.

The findings of detailed angiographic studies in 111 patients with cirrhosis of the liver and 12 patients with thrombosis of the portal system were compared with the angiographic findings in 105 normal people. Definite changes in the haemodynamics of the arterial system of the liver and spleen and of the portal system were observed in patients with cirrhosis. All forms of portal hypertension are characterised by increasing flow in the splenic and left gastric arteries. Arterial flow through the liver is closely correlated with portal pressure. The present angiographic findings confirm the existence of a close interdependence between the arterial and portal systems, which may be regarded as separate limbs of a total unified vascular chain.