This book contains the contributions and discussions of the second symposium on vascular smooth muscles held in Ttibingen in February, 1976. It provides an up-to-date review of the role of ions in the trans mission of signals from the perivascular space to the contractile ele ments of the smooth muscle cells. The various aspects are mainly discussed from a functional point of view and only few contributions concern the morphologic variations of cells .during varying ion activity. Special emphasis was placed on the significance of ion variations in the cerebral tissue and their rela tion to metabolic and nervous control of the brain vessels. It could be seen in this symposium that new techniques enabled the in vestigators to make considerable progress in the understanding of the actions and the interactions of ions on the membranes and on the inter nal structures of the smooth muscle cells if one compares the findings with the results of the previous symposium held in Ttibingen in 1972. It became evident that the insight into ionic actions enables the de velopment of powerful tools to be utilized in future therapy of dis turbances of local blood flow regulation. The participants of the symposium render thanks to the Dr. Thiemann GmbH in Ltinen, which supported the symposium and this publication in a generous way. Finally it is a pleasure of the Editor to thank the members of the Physiological Institute of Ttibingen for their encouragement in the ar rangement of the meeting.

Response Characteristics of K+-, Ca++- and Other Liquid Membrane Electrodes

Serum Ca++-Activity and Complexation
Summary of the Discussion. G. Siegel (Chairman) H. Apfel
Calcium Activation of Vascular Contractile Proteins
Calcium Compartments in Vascular Smooth Muscle: Electron Probe Analysis
Differentiation of Calcium Activation Systems in Vascular Smooth Muscle
La+++ and Excitation Contraction Coupling in Vascular Smooth Muscle
Summary of the Discussion. G. Siegel (Chairman) and H. Apfel
Calcium and Regulation of Cyclic Nucleotides in Rat Aorta
Calcium and the Regulation of Adenosine 3?,5?-Monophosphate by Neurotransmitters
Summary of the Discussion. A. P. Somlyo (Chairman) and C. Infantes
Reaction of Capillary Flow to Electrical Stimulation of the Capillary Wall and to Application of Different Ions
Membrane Basis of Vascular Regulation
Noradrenaline and pH-Effects at the Membrane of Vascular Smooth Muscle
Vascular Effects of Potassium in Physiologic Concentration Range
Summary of the Discussion. W. R. Keatinge (Chairman) and U. Schindler
Calcium in the Vascular Smooth Muscle Cell
Spontaneous Actions of Small Pial Vessels and the Response to Transmural Electrical Stimulation
Ionic Interaction in Pial Vascular Smooth Muscles
Measurements of Pial Perivascular Ion Activities by Means of Ion Sensitive Microelectrodes
The Effects of Serotonin and Noradrenaline on the Pial Arteries
Interactions of Norepinephrine with H+ and K+ at Pial Arteries of Cats
Summary of the Discussion. J. Astrup (Chairman) and G. Karlitzky
The Action of K+ at the Cerebral Vessels
K+ Accumulation as a Pathological Stimulus for Dilatation or Contraction of Cerebral Vessels
H+, CO2, Prostaglandins and Cerebrovascular Smooth Muscle
Correlation ofChanges in Blood Flow and Acid-Base Changes in the Brain during Induced Epileptic Seizures
Evidence against H+ and K+ as the Main Factors in the Regulation of Cerebral Blood Flow during Epileptic Discharges, Acute Hypoxemia, Amphetamine Intoxication, and Hypoglycemia. A Microelectrode Study
Summary of the Discussion. R. M. Berne (Chairman) and D. Heuser
Interactions of H Ions, Ca-Antagonistic Drugs and Cardiac Glycosides with Excitation-Contraction Coupling of Vascular Smooth Muscle
Effect of Phosphodiesterase-Inhibition on Smooth Muscle Tone
The Effect of Bencyclane on the K+- and Ca++- Induced Pial Arterial Constriction
Effect of Adenosine on Contraction of Vascular Smooth Muscle
Influence of pH on Adenosine-Induced Dilatations of Pial Arteries
Effect of Sodium Nitroprusside, Temperature, and Calcium Withdrawal on the Relaxation Speed of Vascular Smooth Muscle
Summary of the Discussion. C. van Breemen (Chairman) and A. Linke
Conclusion.