Rat renal and erythrocyte carbonic anhydrases. Purification and properties.

Rat renal and erythrocyte carbonic anhydrases (carbonate hydro-lyase, EC 4.2.1.1) were isolated by affinity chromatography. The erythrocytes contain two major forms of the enzyme. One of the forms has a specific activity (towards CO2) 30 times higher than the other and constitutes the major part of the total cellular carbonic anhydrase. The amino acid compositions of this high-activity type and of the low-activity type are similar to the compositions reported for these types in other species. The kidney appears to have only one high-activity form of carbonic anhydrase which is very similar to and probably identical with the erythrocyte high-activity form.

Carbonic anhydrase C in the human renal medulla.

Soluble carbonic anhydrase (carbonate dehydratase, EC 4.2.1.1) from the papillary and inner medullary regions of thoroughly perfused human donor kidneys was isolated by affinity chromatography. The purified enzyme was homogenous with respect to sedimentation in the ultracentrifuge and iso-electric focusing. It had an amino-acid composition and behaved chromatographically, kinetically, electrophoretically and immunochemically like the high-activity (with respect to CO2) erythrocyte carbonic anhydrase HCA-C, and the renal enzyme previously isolated from extracts of the whole kidney. The results suggest that all regions of the human kidney contains one soluble form of carbonic anhydrase similar to and probably identical with HCA-C. Small immunoassayable amounts (1/30 of total enzyme protein) of the low-activity erythrocyte isoenzyme HCA-B were also found, but are considered to be a contaminant. There was no indication for the presence of sulfonamide-resistant isoenzymes.

Human renal carbonic anhydrase. Purification and properties.

Carbonic ahyndrase was isolated from fresh human donor kidneys which had been thoroughly perfused free from blood. The isolation procedure involved biospecific affinity chromatography on a sulfanilamide-agarose column and yielded one soluble form of the enzyme, which was homogenous with respect to sedimentation in the ultracentrifuge, electrophoresis, isoelectric focusing and immunodiffusion. The renal enzyme had an amino acid composition and beahved chromatographically, electrophoretically, and immunochemically like the erythrocyte form human carbonic anhydrase C, isolated by the same technique. The kinetic behaviour of the renal enzyme was similar to that of human carbonic anhydrase C when compared by the stopped-flow pH-indicator technique. The results therefore suggest that the cytoplasmic carbonic anhydrase of the human kidney is very similar, if not identical, to the high-activity erythrocyte form of human carbonic anhydrase C.

Increasing caesarean section rate.

At the University Hospital in Uppsala 719 Caesarean Sectons (C.S.) were performed 1966-1970. The total number of deliveries was 16 708. The C.S. rate increased from 2.0% to 7.8%. This trent was mainly due to an increasing frequency of C.S. performed for cephalopelvic disproportion fetal distress "bad obstetrical history" and failed induction of labour with intravenous oxytocin drip. No maternal deaths occurred. The perinatal mortality was 5.0%. In infants with a birth weight of 1 500 g or less the perinatal mortality was 57% and in infants with a birth weight of more than 2 500 g and a gestational age of 37 weeks or more it was 0.9%. In 207 elective C.S. on healthy mothers at term no perinatal deaths were noted.

A radioimmunosorbent technique for the assay of B- and C-types of carbonic anhydrase in human tissues.

A radioimmunosorbent technique for the assay of the human carbonic anhydrase isoenzymes HCA B and HCA C in tissue fluids was developed. The sensitivity of the method was 0.2 ng/ml and the precision was 5% in duplicate determinations for both enzymes. The presence in a tissue of up to 20 times higher concentrations of one isoenzyme will not interfere with the assay of the other. Haemolysates contained (mean +/- SE, n = 11) 12.1 +/- 0.52 and 1.5 +/- 0.06 mg enzyme/g Hb, and serum 0.63 +/- 0.12 and 0.2 +/- 0.02 microgram/ml of HCA B and HCA C, respectively. Pilot experiments indicated that the isoenzymes can be determined also in tissues, i.e. urine, saliva and cerebrospinal fluid, where catalytic methods previously have indicated absence of or only weak carbonic anhydrase activity. N-terminals of both enzymes were not antigenic.