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Serum and brain tissue concentrations were determined after i.v. administration of 4 g cephradine to 11 patients of whom 6 were additionally receiving 40 mg furosemide t.i.d. peroral. Five further patients were given 4 g cephalothin i.v. All patients were undergoing a brain operation at the time of antibiotic administration. Between 60 and 100 min after dosage, cephradine decreased in the serum from 104.9 mcg/ml to 56.7 mcg/ml and in the brain tissue from 13.02 mcg/g to 8.37 mcg/g in the mean. Cephradine concentrations in serum were higher and in brain tissue lower when furosemide was given as well. These differences are statistically significant (p less than 0.01). Serum concentrations of cephalothin over the same period and in the absence of furosemide were very low with 32.2 mcg/ml at 60 to 70 min, and extremely low in the brain tissue (0.55 mcg/g in the mean) so that a trial with furosemide was not performed. Neither antibiotic was detectable in the cerebrospinal fluid. The differences in serum and brain tissue concentrations of cephradine in the presence and absence of furosemide demonstrate that special care must be taken when administering more than one drug.

On 11 isolated dog hearts, perfused with arterial blood of a donor dog, the degree of hypoxic dilatation and the maximum coronary blood flow achieved by adenosine were compared. The maximum coronary blood flow under adenosine infusion amounted to 455ml/minx100g, that means an increase of about 600% of the normal flow. If coronary venous pO2 was below 5mm Hg coronary blood flow was increased to 420ml/minx100g, which is 93% of the pharmacologically achieved maximum increase of the coronary blood flow. The difference between the maximum hypoxic and the maximum pharmacological dilatation is due to the method; it is caused by an increase of the extravascular component of coronary resistance under the influence of catecholamines in the case of hypoxic dilatation. It is pointed out that in order to achieve a maximum hypoxic dilatation oxygen pressure has to be below the critical value. It can be concluded that the intravascular component of coronary resistance is as low under hypoxic as under pharmacological dilatation.

A new developed partial artificial heart system is presented, which allows pulsatile perfusion of vital organs. The results presented reveal the possibility to duplicate pressure curves and peak systolic pressure in the perfused area-similar to physiological preoperative measurements. The kidney function remains intact. Angiographically there is no damage of the kidney vessels evident. The results are compared with datas of other investigators. Especially there opinion about the disturbance of renal flow and function under nonpulsatile conditions are critically evaluated. A possible connnection between the postoperative renal failure after cardio-pulmonary bypass and non-pulsatile perfusion and other pathophysiological mechanisms are discussed.

The influence of an increased Ca concentration on reactive hyperemia, work induced vasodilation and pharmacologically induced dilation (adenosine, nifedipine, verapamil) was studied in the blood perfused gastrocnemius of dogs. Reactive hyperemia, work induced vasodilation and increased blood flow by administration of adenosine could not be influenced by increased extracellular Ca concentrations. A Ca antagonism was demonstrated for nifedipine and verapamil, especially with regard to a diminution of the drug eff.