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We investigated the functional and hemodynamic effects on the kidney of tris (hydroxymethyl) amino methane (THAM) infusion during sustained hemorrhagic hypotension in dogs. The large osmotic load introduced into the vascular compartment during hemorrhagic hypotension resulted in a marked reduction in systemic vascular resistance and a return of cardiac output, total renal blood flow, and the renal arteriographic pattern to normal range. The observed diuresis is probably due to an osmotic effect, because the glomerular filtration rate remains significantly depressed. Anatomical assignment of the mathematical components of the xenon washout curve led to an assessment of intrarenal blood flow distribution that was at variance with the arteriographic pattern and the intrarenal distribution of tagged microspheres.

After dissociation of the E. coli recBc DNase (ATP-dependent DNase) with concentrated NaCl, two subunit proteins were isolated by ion exchange chromatography. Combination and subsequent incubation of the subunits resulted in the appearance of the original DNase. The subunit proteins, designated alpha and beta, have s(20,omega) of 4.1 S and 8.1 S, respectively. The alpha subunit possesses neither the ATP-dependent Dnase nor the DNA-dependent ATPase of the original enzyme. The beta subunit contains a low level of both enzymatic activities in a ratio markedly different from that of the original enzyme. The beta subunit complemented extracts from both recB and recC mutant strains to produce recBC DNase, while the alpha subunit did not complement either extract. These results suggest that recB and recC genes are both required for the production of beta subunit and that the recBC DNase molecule contains a protein component (alpha) that is not determined by either the recB or the recC gene.

The antibody response of mice to alpha-1,3 linked dextran is shown to be controlled by a heavy chain variable region gene, VH-DEX. The map distance between this gene and the heavy chain allotype locus is estimated to be 0.3 recombination units.

The frequency of lymphocytes bearing complement receptors in the spleens of 2-wk old mice appears to be controlled by two independent genes. The presence of a "high" allele at either locus leads to intermediate or high frequency of CRL at 2 wk of age. One of the genes controlling complement receptor lymphocyte (CRL) frequency (CRL-1) is linked to the H-2 complex. Thus, in progeny of (AKR x DBA/2)F(1) x DBA/2, all mice with a low frequency of CRL at 2 wk of age are homozygous for the H-2 type of the low CRL parent (DBA/2). Furthermore, in the B10 series of congenic mice, CRL frequency at 2 wk of age is similar to the frequency in the donor of the H-2 region. Thus, C57BL/10, B10.BR, and B10-D2 mice are all of the low CRL type while B10.A mice are intermediate in CRL frequency at 2 wk. C57BR and DBA/2, the donors of the H-2 complex of the B10.BR and B10.D2, respectively, are of low CRL type while the A/WySn, the donor of the H-2 complex in the B10.A, is an intermediate CRL strain. Similarly in the A/WySn series of congenic mice, A.CA, A.SW, and A.BY are all low CRL strains while the A/WySn is intermediate. Studies of CRL frequency in mice with recombinant H-2 chromosomes (B10.A(2R), (4R), and (5R); B6/TL(+); and A/TL(-)) indicate that CRL-1 is to the right of the Ss-Slp genes and to the left of Tla.

The effect of altered tubular sodium reabsorption on renin secretion (RSR) was examined under conditions in which other factors influencing renin release could be controlled or excluded. To do this, isolated canine kidneys were perfused at constant pressure with blood circulating from donor animals. Volume expansion or hemorrhage of the donor dogs produced large changes in the animal's blood pressure, renal function, sodium excretion (UNaV), and RSR, but were without effect on renal hemodynamics, UNaV, or RSR in the perfused kidney. Hemodilution without volume expansion, resulted in hypotension, decreased UNaV and increased RSR in the donor dogs, and increased UNaV and suppressed RSR in the perfused kidney. These effects of hemodilution in the perfused kidney were partially reversed when plasma protein concentration was restored to control levels with hyperoncotic albumin, and, overall, there was a significant inverse relationship between electrolyte excretion and RSR. These results provide new evidence for the hypothesis that the rate at which sodium is delivered to the macula densa is an important determinant of the rate of renin secretion.

The relationship between receptor molecules on antigen-binding lymphocytes (ABC) and antibody produced by antibody-secreting cells was studied in inbred strains of mice using the immune response to phosphorylcholine (PC) as a model system. Splenic and lymph node lymphocytes of nonimmune mice possess rare lymphocytes which bind (125)I-labeled PC-bovine serum albumin. The frequency of PC-ABC increases after immunization and is paralleled by a rise in the frequency of PC-specific antibody-producing cells. Both of these responses are thymus independent. The receptors on these ABC display specificity for PC and are exclusively of the IgM class. In one of the strains, BALB/c, the receptors possess the same idiotype and fine degree of specificity for PC and two of its analogues, glycerophosphorylcholine and choline, that are characteristic of a PC-binding myeloma, HOPC 8. Furthermore, the idiotype and class of the receptor in these mice do not change during the course of the immune response. These data provide more direct evidence for the immunelogic relevance of receptor-bearing lymphocytes.

Splenic macrophages were identified as at least one source of C5 elaboration in normal mice. Hybrid cells were formed from splenic macrophages from C5-deficient mice and either kidney cells from mice with normal amounts of C5 or chicken erythrocytes. These hybrids elaborated C5 in vitro. C5-Deficient mice inoculated with these hybrid cells developed, in their serum, antigenically active mouse C5, as well as both hemolytic and biologic complement activity. These studies demonstrate the feasibility of genetic "repair" in mammals.