The Role of the Membrane Potential of Endothelial and Smooth Muscle Cells in the Regulation of Coronary Blood Flow

Membrane Potential of Coronary Endothelial and Smooth Muscle Cells. In the mammalian heart the supply of oxygen and energy-rich substrates through the coronary arterioles is continuously adapted to the variations of cardiac work. The coronary resistance arteries and the surrounding myocardium form a functional unit with multiple interactions between coronary endothelial cells, smooth muscle cells, perivascular nerves, and cardiac muscle cells. We describe the mechanisms underlying the electrical and chemical communication between the different cell types, the ionic channels contributing to the resting potential of endothelial and smooth muscle cells, and the mechanisms responsible for modulation of the resting potential. The main conclusion of our analysis is that the membrane potential of coronary endothelial and smooth muscle cells is one of the major determinants of coronary blood flow, and that modulation of the membrane potential provides a way to dilate or constrict coronary resistance arteries. It is proposed that the membrane potential of the myo-endothelial regulatory unit, i.e., of the endothelial cells and the underlying smooth muscle cells in the terminal arterioles, may function as an integrator of the numerous local and global vasodilator and constrictor signals that provide for the adaptation of coronary blood flow to the metabolic demands of the heart.     

THERAPEUTIC SUGGESTIONS DURING GENERAL ANAESTHESIA IN PATIENTS UNDERGOING HYSTERECTOMY

In a double-blind, randomized study, we have examined the influenceof positive therapeutic suggestions, presented to anaesthetizedpatients undergoing total abdominal hysterectomy, on postoperativemorbidity and duration of hospital stay. Seventy-five patientswere allocated randomly to be exposed to one of three tapescontaining positive therapeutic suggestions, a modified historyof the Queen's Medical Centre, or no message. We found thatneither therapeutic suggestions nor the presence of a voiceduring anaesthesia improved postoperative outcome or reducedduration of hospital stay after total abdominal hysterectomy.     

Retention of auditory information presented during anaesthesia

Surgical procedures that involve a local anaesthetic block are often accompanied by light general anaesthesia. It is possible that under these circumstances, the patients are more likely to register auditory events while apparently unconscious. Two groups of children were exposed to auditory stimuli during surgery; one group received a lighter level of anaesthesia than the other. Retention of the stimuli was tested using a cued recall technique, and the performance of the two experimental groups was compared with a control group which had not been exposed to the material but was tested in the same way. The light anaesthesia group retained more items than did the other two groups but this difference was significant (p less than 0.05) only when compared with the other experimental group. This is not very strong evidence of auditory registration, but a greater effect might be found with exposure to emotionally significant material. It is suggested that patients should be protected from unfortunate theatre conversation.