This special issue of Acta Physiologica contains review articles (and two original articles) based on the lectures given at the symposium ‘Frontiers in Physiology’ held at the Royal Danish Academy of Sciences and Letters in Copenhagen, Denmark, 15–16 May 2008. The symposium was supported by the American and Scandinavian Physiological Societies as well as the Royal Danish Academy. The conference was held in honour of Ole Holger Petersen on the occasion of his 65th birthday and also marked the 20th anniversary of his election as a Foreign Member of the Royal Danish Academy.

Ole graduated from The University of Copenhagen and subsequently worked at this University for some years before leaving for the UK in 1975. He is currently Medical Research Council Professor at Liverpool University. In the 1970s and early 1980s, Ole was the first to identify and characterize Ca2+-activated ion channels in epithelial cells. Later, a combination of electrophysiological and Ca2+-sensitive fluorescence measurements resulted in discoveries of local cytosolic Ca2+ signals, the Ca2+ tunnel function of the endoplasmic reticulum as well as the role of mitochondria in shaping Ca2+ signals. These achievements have been recognized widely, most significantly by Ole’s election as a Fellow of The Royal Society in 2000 and his appointment by Queen Elizabeth II in 2008 as Commander of the British Empire for ‘Services to Science’.

A major part of this symposium was devoted to cellular and molecular physiology. Bernd Nilius provided new insights into the role of TRPC channels in inflammation, whereas Anant Parekh reveals how Ca2+ entry through CRAC channels can activate temporally and spatially separated events. Javier Garcia-Sancho described how the use of targeted aequorins can give information about Ca2+ signal modulation by various organelles and Oleg Gerasimenko described recent data dealing with the relationship between nuclear Ca2+ signals and the regulation of early response genes. New information about the role of actin-binding proteins in Ca2+ signal generation was provided by Luigia Santella.

Neurobiology features prominently. Denis Burdakov presented recent data on glucose-inhibited neurones, which play an intriguing role in appetite and sleep regulation. Arthur Konnerth synthesized current knowledge concerning the mechanisms by which metabotropic glutamate receptors mediate synaptic signalling in mammalian central neurones, whereas extra-synaptic volume transmission was covered by Eva Sykova, who compared different techniques of measuring diffusion parameters in the brain. Carl Petersen has pioneered functional imaging of the sensorimotor cortex of behaving and, in some cases, even freely moving animals. He reviewed this work and looked forward to the future of genetic manipulation – in combination with electrophysiology and imaging – for unravelling brain function. Glia cells, which make up such a large proportion of the brain, were dealt with by Alexei Verkhratsky, who described how consideration of neuronal-glial circuits can help unify the reticular and neuronal theories of brain organization.

Our understanding of endocrine secretion mechanisms is largely derived from studies of isolated cells, but progress is now being made by using more intact preparations as described in the study of insulin-secreting cells in pancreatic slices by Marjan Rupnik. Andras Spät discussed new aspects of mitochondrial function in endocrine control mechanisms focusing particularly on Ca2+ microdomains.

In the section on epithelial function, Kim Barrett dealt with the crucial question of how epithelial cells decode signals controlling intestinal transport. Kim Barrett’s work provides new insights into the critical role of epidermal growth factor receptors, which are described in the article by McCole and Barrett. Erik Hviid Larsen described regulation of epithelial isotonic fluid transport, focusing on the role of the lateral intercellular space as an osmotic coupling compartment. The physiology and patho-physiology of pancreatic acinar cells were dealt with in lectures on mitochondrial function by Alexei Tepikin and on the role of lipids in the disease acute pancreatitis by Irene Schulz. Finally, I held a presentation about the control of total body sodium, discussing new data and theories of internal signalling and output control.

On behalf of the Scandinavian Physiological Society, I would like to express the hope that readers of Acta Physiologica will enjoy this ‘Festschrift’ for Ole Petersen and that the different perspectives on the frontiers of physiology will stimulate much experimental work that will help to further our understanding of the function of the body.