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Acta vet. scand. 1968, 9, 183-198.
From the Department of Pharmacology and Toxicology, Royal Veterinary and Agricultural College, Copenhagen, Denmark.
RENAL CLEARANCES IN PIGS
INULIN, ENDOGENOUS CREATININE, UREA, PARA-AMINO-
HIPPURIC ACID, SODIUM, POTASSIUM, AND CHLORIDE
By N. Gyrd-Hansen
The increasing interest during recent years in the use of pigs in experimental biological research has necessitated a deeper knowledge of the basic function of a number of organs, including the kidneys. The first report on the kidney function of pigs ap- peared in 1953 when Dalgaard-Mikkelsen et al. described the renal clearance of inulin, sulphadimidine and sulphathiazole. Subsequently, Munsick et al. (1958) provided data from experi- ments on 4 "miniature" pigs, while Vogel (1959a, b) and Ketz (1960a, b) described the results of classical kidney function tests on sucking pigs and young pigs. The aim of the present work was to establish normal values for renal clearance in Danish Landrace pigs of the ages 3 to 8 months.
MATERIAL AND METHODS The examinations were carried out on 31 clinically healthy female pigs of Danish Landrace, weighing from 28 to 123 kg. All the animals were fed during the whole period with a commercial
fodder mixture consisting of 75 % barley, 6 % oats, 10 % soy
meal, 5 % skimmed milk powder, 3 % meat- and bonemeal,
0.2 % mixture of vitamins A, B, D and E, and 0.8 % mineral salt,
consisting of 60 % calcium carbonate, 20 % dicalcium phosphate,
15 % sodium chloride, 3.5 % copper sulphate, 0.75 % zinc car-
bonate,^ 0.625^ %manganese oxideand^ 0.125^ % cobalt^ sulphate.
When thepigswerekilled,thekidneysand^ the^ urinarysystem wereexamined macroscopicallyandall^ were^ found^ tobenormal.
Clearances
Theexperiments were performed^ on^ unanaesthetized^ animals which had free access to^ water before^ commencement of the study. During the experiments the pigswere^ laid on^ their ab- domens onaslatted table to which^ they^ were^ fastenedby^ means ofstrapsovertheneck andback. Blood specimens weretaken^ at^ 20-min.^ intervalsthrough a thin plastic catheter (Intracath®)^ inserted^ into a^ vein in the right ear. Clotting was^ preventedwith heparin, and^ the blood was centrifuged within^2 hrs.^ Plasma was^ used^ for analysis. The urine wascollectedquantitativelythrougha^ ballooncatheter (Riisch no. 14,^30 ml)^ inserted^ into^ thebladder.Thiswasemp- tiedat 20-min.^ intervals^ and, inorder^ to^ ensurecomplete^ eva- cuation,the bladder^ was^ washed^ with^30 mlof^ distilled^ water. Each experiment consisted^ ofatleast^3 periods. In the experiments^ where^ continuous^ intravenous^ infusion (Sigmamotor®^ infusion^ pump) ofinulinsolution orof^ a^ solu- tion containing^ both^ inulin^ andPAH^ (para-aminohippuric^ acid) was^ carried^ out,this^ wasdonethroughaplastic^ catheter^ inserted intoa veinin^ theleft^ ear.The^ primingdose^ ofinulin^ was^ about 40 mg/kg^ andof^ P AHabout^11 mg/kg,^ bothdissolvedin^50 ml of distilled water. After priming,the^ inulin^ andPAH,^ dissolved
in a 0.6 %^ sodium^ chloride^ solution,^ were^ infused^ ata rateof
3 ml per^ min.^ (inulin^ 0.3^ mg/kg/min.^ andPAH^ 0.2^ mg/kg/min.). The first experimental period^ was^ commenced^30 min.^ after^ in- fusion ofthe primingdose. The analytical methods^ used^ were^ as^ follows:
Inulin: Brun (1946),^ endogenous^ creatinine:^ Bonsnes^ &^ Taussky
(1945), PAH:^ Bratton^ &^ Marshall^ (1939),urea:^ Conway^ (1950),
chloride: Schales &^ Schales^ (1941).^ Potassium^ and^ sodium^ were
determined by flame^ photometer^ (Beckman^ Direct^ Reading^ Flame Photometer). All the plasma^ concentrations^ found^ were^ calcul- ated to correspond to the^ values^ at^ the^ water^ phase^ of^ the^ plasma, the content of dry matter^ in^ plasma^ being^ considered^ to^ be^8 %. The haematocrit values were^ determined^ in^ micro-haematocrit tubes after centrifugation^ in^ a^ MSE^ Micro^ Haematocrit^ Centri- fuge for^15 min.^ at^4500 r.p.m.
00
T a b I e
Renal
clearance
of
inulin,
endogenous
creatinine
and
urea.
Q)
Pig
Body
Kidney
Diuresis
lnulin
Enrlogen.
creatinine
Urea
Clearance
no.
weight
weight
ratios
kg
g^
ml/min.
ml/min./
ml/min/
ml/min./
ml/min./
ml/min./
ml/min./
ml/min./
100
g
10
kg
100
g^
10
kg
100
g
10
kg
100
g
Cr/In
Urea/In
kidney
b.wt.
kidney
b.wt.
kidney
b.wt.
kidney
17
28
109
23
(18-27)
57
19
(16-22)
49
16
(12-19)
41
24
30
115
21
(20-23)
55
20
(17-23)
52
11
(10-12)
29
18
33
125
22
(21-23)
58
19
(17-20)
48
11
(10-12)
30
19
39
142
20
(19-21)
55
19
(19-19)
51
10
(
7-13)
28
20
43
167
21
(17-24)
54
16
(14-26)
41
11 (
8-14)
29
21
49
178
25
(23-27)
69
19
(17-21)
53
18
(15-21)
49
22
58
207
21
(15-27)
59
23
(17-28)
63
11
(
9-14)
31
23
63
223
20
(16-22)
55
18
(16-22)
50
10
(
9-11)
28
15
69
242
21
(20-23)
60
26
(24-28)
74
13
(12-14)
37
8
84
289
20
(18-23)
57
24
(21-27)
70
13
(11--14)
38
3
86
296
18
(18-20)
54
16
(15-17)
46
11
(10-12)
32
1
90
308
18
(15-20)
53
15
(12-16)
43
11
(
9-13)
32
25
117
420
19
(17-20)
51
17
(15-18)
46
11
(10-11)
30
26
123
440
19
(18-20)
53
17
(17-18)
48
11
(10-11)
30
The
bracketed
figures
indicate
the
min.
and
max. values
of
single
periods.
JO
0 (^20) >gti. •^ Q.^ x^ •^ • x.x^ • 0 A^ ti.A
//)
/) (^200) 'tlllJ 41111 Bdll 11100 1200 l'tl/O 141/() (^181111) cOOIJ F i g u r e 2. Inulin clearance at different concentrations of inulin in plasma. Ordinate: Clearance ml/min./10 kg b. wt. Abscissa: Concentrations of inulin in plasma μg/ml. e Pig no. 24 0 Pig no. 27 6 Pig no. 28 X Pig no. 30
thereby obtaining inulin concentrations in plasma varying from 40 to 1900 μg/ml. The urine flow varied only slightly in each experiment. The results are given in Fig. 2, which shows that the clearance per 10 kg body weight of the individual pigs was con- stant within the concentration range mentioned. Effect on inulin clearance of variations in diuresis. The in- fluence of the rate of urine flow on inulin clearance was examined in experiments on 4 pigs. Urine flow was constant during each period but varied in the experiments from 0.07 to 1.91 ml/min./ 10 kg by giving water at body temperature per os and infusion of P AH solution. The inulin concentration in plasma was constant
( ± 10 % ) in these experiments. It was found that the clearance
of inulin was independent of the degree of diuresis (Fig. 3). Clearance of inulin, endogenous creatinine and urea. Table 1 shows the results of 14 experiments in which clearances of inulin, endogenous creatinine and urea were determined simultaneously. The concentrations of the test substances in plasma were con-
stant(± 10 % ) in each experiment. The lowest and highest inulin
concentrations were 108 μg/ml and 201 μg/ml, respectively, while the content of urea and creatinine in plasma varied between 241 and 588 μg/ml and between 7 and 19 μg/ml, respectively. Urine flow varied from 0.2 to 2. 7 ml/min. It will be seen from the table that the clearances of inulin, creatinine and urea calculated per 10 kg body weight and 100 g kidney were constant in pigs weigh-
Table 2. Clearance of para-aminohippuric acid andthe filtration fraction.
Pig Body Diuresis Inulin PAH PAH Filtration no. weight ml/min.^ clearanre^ clearance^ clearance^ fraction kg ml/min./ ml/min./ ml/min./ C1n/CPAH 10 kgb.wt.^10 kg^ b.wt.•)^100 g kidney*")
24 30 0.2 21 56 (52-60)^146 0. 19 39 0.5 20 84 (72-92)^229 0. 20 43 1.1 21 59 (52-72) 152 0. 21 49 1.0 25 79 (74-87)^216 0. 22 58 0.9^2169 (56-86)^194 0. 23 63 1.0 20 53 (47-60)^152 0. 25 117 1.6 19 58 (54-63) 158 0. 26 123 1.7 19 52 (48-58)^146 0.
*) The bracketed figures indicate the min. and max. values of single periods. **) Calculated from the relative kidney weight^ 0.36^ %.
minedat^ thesametime,itwaspossible^ to^ calculatethepartof the plasma- the^ filtration^ fraction- whichis^ filteredthrough theglomeruli (C 1 n/CPAH).Table^2 shows that^ theaverage fil- tration^ fraction^ was0.33,varying^ from^ 0.24^ to^ 0.37. Maximal tubular PAH excretion. The maximal^ excretion (Tm)of PAH was determinedin 10 experiments on^7 pigsduring loadingwithPAH. In 7 casesthe experiments started^ with^ the determination of PAH clearancein 3 periods of^20 min.^ witha small PAH concentrationin plasma(10-24μg/ml).^ In^ theload- ing experiments the^ primingdose^ was^ about^500 mg/kg^ and^ the maintenance dose about 5 mg/kg/min., thereby^ obtaining^ high P AHconcentrationsin plasma^ (Table^ 3).^ Theexperiments that commenced with determinationof^ CPAHwithlow^ PAH^ concen- tration in plasma showedthat the P AH clearancein^ the^ same animal was considerably lessduring^ loading^ withP AHthan^ with a P AH content in plasma^ of^ about^20 μg/ml. On the basis of PAH clearance^ (CPAH) during^ loading^ with PAH and the inulin^ clearance^ (C1n)^ measured^ simultaneously, the maximal tubular excretion^ was^ calculated^ from^ the^ formula
Tm= (CPAH-Cin) X PPAH
where^ PpAH^ is^ the^ P AH^ concentration^ in^ plasma.^ As^ will^ be^ seen from the last column^ of^ Table^ 3,^ the^ calculated^ Tm^ values^ vary from 17 to 37 mg/min./10^ kg^ body^ weight^ or^ from^47 to^100 mg/
Table 3. Clearance and maximal tubular excretion (Tm) (^) of para- aminohippuric acid*).
Pig Body Plasma PAH lnulin Tm Tm no. weight concentr atlon clearance clearance mg/min./ mg/min./ kg of PAH (^) ml/min/ ml min./ 10 kg b wt. 100 g μg/ml 10 kg b.wt.^10 kg^ b.wt^ kidney**)
24 30 1340 37 22 20 49 27 32 585 61 22 22 61 28 40 1340 32 16 22 61 29 47 1207 47 21 31 86 30 61 931 63 23 37 100 25 79 1426 30 16 20 56 26 81 1503 24 13 17 47 26 100 1545 34 18 24 67 25 117 1673 30 17 23 64 26 123 1766 25 14 19 53
*) (^) The figures indicate the average for 3 periods. **) (^) Calculated from the relative kidney weight 0.36 o/o.
min./100 g kidney, with an average of 23 mg/min./10 kg or 64 mg/min./100 g kidney. Extraction percentage for PAH. The experiments were carried out on pigs anaesthetized with phencyclidinum NFN (1.5 mg/kg intramuscularly) combined with inhalation of halothanum NFN. A solution of PAH was infused during th.e whole experiment through a catheter inserted into a vein in the left ear. The priming dose was 35 mg/kg and the maintenance dose 0.6 mg/kg/min. A plastic catheter was led through the femoral artery along the aorta to the source of the renal artery, from which site arterial blood was taken. Blood from the right vena renalis was taken through a plastic catheter inserted into the vein after laparotomy.
Table 4. The renal extraction of para-aminohippuric acid. Concentration of PAH in plasma from Pig Body A. renal. V. renal. Extraction no. weight μglml μg/ml of PAH
kg O/o
30 61 102.5^ 8.8^91
Pig no.
Table 6. Renal excretion of electrolytes. Body^ Diuresis^ Clearance^ Excretion^ O/o weight ml/min. kg Jnulin^ Sodium^ Potassium Chloride^ Sodium^ Pot^ as-^ Chloride ml/min./ ml/min./^ ml/min./^ ml/min./^ sium 10 kg 10 kg^10 kg^10 kg b.wt b.wt. b.wt. b.wt.
28 0.4 23 0.009 1.2^ 0.02^ 0.04^ 5. 30 0.2^21 0.038^ 1.0^ 0.06^ 0.18^ 5. 33 0.4^22 0.004^ 1.1^ 0.03^ 0.02^ 5. 39 0.5 20 0.002 1.5 0.07^ 0.01^ 7. 43 1.1 21 0.005 1.2^ 0.05^ 0.02^ 5. 49 1.0 25 0.003^ 1.9^ 0.10^ 0.01^ 7. 58 0.9^21 0.004^ 2.5^ 0.03^ 0.02^ 11. 63 1.0^20 0.005^ 2.7^ 0.07^ 0.03^ 13. 69 1.7 21 0.039 3.2 0.30^ 0.19^ 15. 84 2.7 20 0.007 3.8^ 0.20^ 0.04^ 19. 86 1.7^18 0.005^ 2.4^ 0.08^ 0.03^ 13. 90 1.7^18 0.071^ 1.7^ 0.08^ 0.39^ 9. 117 1.6 19 0.025 2.0 0.03^ 0.13^ 10. 123 1.7 19 0.018 0.9 0.02^ 0.09^ 4.
experiment.Theaverage blood flowwas^133 ml/min./10^ kg^ body weight or 363 ml/min./100 g kidney.
Excretion of sodium,^ potassium^ and^ chloride.^ The^ renal
clearances^ of^ sodium,^ potassium andchloride^ were^ determined in26 pigs,theaverage values^ being^ 0.015,^ 2.8and^ 0.11^ ml/min./ 10 kg body weight, respectively.Jn^14 ofthepigstheelectrolytic excretion^ was^ measured^ simultaneously^ with^ the^ inulinclearance; the results aregiveninTable6.The^ table^ showsthepercentage excretion of sodium,^ potassium^ andchloride,and^ it^ will^ be^ seen that they^ vary^ considerably^ from^ animal^ to^ animal.Thechloride clearance was^ constant^ in^ the^ various^ experimental^ periods^ for the same pigs.^ However, the^ sodium^ and^ potassium^ excretion varied somewhat;^ as^ regards^ sodium,theexcretion^ was^ generally slightly lowerat the^ end^ of^ the^ experiment. The concentrations^ of^ the^3 electrolytesin^ plasma^ were^ quite constant during^ the^ experiments.^ The^ variations^ from^ pig^ to^ pig in the content of electrolytes in^ plasma^ were^ negligible,^ the average content of sodium,^ potassium^ and^ chloride^ in^26 pigs being 146 mEq/l (min.^ 132,^ max.^ 158),^ 4.2mEq/l^ (min.^ 3.6,^ max. 4.8) and 109 mEq/l^ (min.^ 104,^ max.^ 116)^ respectively.
DISCUSSION
Inprevious publicationson renalclearance ofinulininpigs (Dalgaard-Mikkelsen et al. 1953; Munsick et al. 1958; Vogel 1959a,b; Ketz 1960a, b) itwas assumedthatinulinclearanceis anindication oftheglomerular filtration,asis thecaseinother animalspeciesandin man(see Poulsen 1957, Knudsen 1959, Pitts 1965). As will be seenfromtheresults ofthe presentstudy,that assumption is justified, since in pigs also inulin clearance is independentofboth plasmaconcentrationand the rateofurine flow.Forease of reference,theclearances of inulin, endogenous creatinine,urea and P AHareassembledinTable7.
Table 7. Averagerenalclearancesinpigs.
Inulin Endogenouscreatinine Urea Para-aminohippuric acid
Number of pigs
14 26 26 8
ml/min./ 10 kg b.wt. 21 (18-25) 22 (15-34) 12 (9-18) 64 (52-84)
Clearance ml/min./ 100 g kidney
56 (51-69) 61 (41-93) 34 (27-49) 174 (146-229) The bracketedfiguresindicatemin.andmax. values of single experi- ments.
Inulinclearanceinpigswas 21 ml/min./10 kg body weight (18to25) or 56 ml/min./100 g kidney (51 to 69), values which remained constant, eventhough thebody weight ofthe animals varied from 28 to 123 kg.They are identical withthose reported by Ketz (1960a, b) for pigswitha body weight of 25 and 50 kg. However,the inulin clearance of 67 ml/min./100 g kidney found by Ketz (1960b) is somewhat higher than that found in the present material, presumably because the relative kidney weight was lessin thepigs used by Ketz. Munsick et al. reported (^) that the inulin clearance for pigs weighing 20 kg ("miniature" pigs from the Hormel Institute of Austin) was 49 to 53 ml/min./10 kg but that this clearance seemed to be very high for animals ofthat size. In Dalgaard-Mikkelsen et al.'s study it is stated that the inulin clearance of pigs weighing between 15 and 43 kg is 36. ml/min./10 kg. Before the start of the experiment the (^) pigs had been given urethane orally as a sedative, and thus the results cannot be compared directly with those obtained in the present study where unanaesthetized pigs were used.
tration fraction is 0.16 to 0.20 in man and 0.20 to 0.30 in dogs
(Pitts), while in horses, sheep and goats it is between 0.11 and
0.17 (Vogel 1962).
The percentage extraction of P AH has been found to be 87 %,
which corresponds to the value found in man, while in dogs it is
75 to 80 % (Pitts).
The average total renal blood flow is 133 ml/min./10 kg body weight, varying from 115 to 160 ml/min./10 kg, or from 300 to 440 ml/min./100 g kidney. This is of the same order of magnitude
as in man (Pitts). Ketz (1960a) reports that the effective renal
blood flow in pigs weighing 51 kg is 421 ml/min./m 2 surface.
However, Ketz (1960a) calculated the renal blood flow according
to the formula
RBF = (100 + haematocrit % ) X RPF
while that used in the present study is
RBF = R_P_F_X_l_OO
100 - haematocrit %
If this latter formula is used to calculate the effective renal
blood flow in Ketz's work (1960a), a figure of 514 ml/min./m 2
surface is obtained instead of 421. If this effective renal blood flow is converted to total renal blood flow per 10 kg body weight, since a pig weighing 51 kg has a surface of 1.35 m 2 , and according to our findings the extraction percentage for PAH is 87, a figure of 157 ml/min./10 kg is obtained. This corresponds to the highest values in the present study (Table 5). The maximal tubular excretion of P AH found, viz. 23 mg/
min./10 kg, is slightly lower than that stated by Munsick et al.,
viz. 31 mg/min./10 kg (2 miniature pigs). For the sake of com- parison, it can be mentioned that the Tm of P AH in man and dogs is generally given as 12 and 10 mg/lnin./10 kg body weight, respectively (Smith 1956). It can be added that in some cases inulin clearance is decreased considerably during loading with P AH. Similar observations have been made previously by other workers (see Smith 1951). The clearance values for sodium, potassium and chloride are
about the same as Ketz ( 1960a) found in experiments on pigs
weighing 25 and 50 kg.
REFERENCES Bonsnes, R. W. & H. H. Taussky: On the colorimetric determination of creatinine by the Jaffe reaction. J. biol. Chem. 1945, 158, 581-
Bratton, A. C. & E. K. Marshall: A new coupling component for sul- fanilamide determination. J. biol. Chem. 1939, 128, 537-550. Brun, C.: In Iversen, P., T. Bjering & J. Bing: De medicinske nyre- lidelser. 2. udg., Kj.'.lbenhavn 1946, pp. 83-85. Conway, E. J.: Microdiffusion analysis and volumetric error. 3rd Ed., London 1950, p. 152. Dalgaard-Mikkelsen, S., E. Poulsen & B. Simesen: Sulfadimidin og sulfatiazol til ungsvin. Nord. Vet.-Med. 1953, 5, 965-981. Iversen, P., T. Bjering & J. Bing: De medicinske nyrelidelser. 2. udg., Kj.'.lbenhavn 1946, pp. 78---82. Ketz, H.-A.: Untersuchungen zur Nierenfunktion und renalen Elektro- lytausscheidung beim Schwein. Arch. exp. Vet.-Med. 1960a, 14, 290-305. Ketz, H.-A.: Vergleichende Betrachtungen zur Nierenfunktion bei den Haustieren. Zbl. Vet.-Med. 1960b, 7, 411-419. Knudsen, E.: Renal clearance studies on the horse I. Acta vet. scand. 1959, 1, 52-66. Munsick, R. A., W. H. Sawyer & H. B. uan Dyke: The antidiuretic potency of arginine and lysine vasopressins in the pig with observations on porcine renal function. Endocrinology 1958, 63, 688-693. Nielsen, Ole E.: Den renale kaliumudskillelse. Kj.'.lbenhavn 1968, pp. 31-37. Pitts, R. F.: Physiology of the kidney and body fluids. Chicago 1965, pp. 64-65 and 132-133. Poulsen, E.: Renale hos kj.'.ler. Kj.'.lbenhavn 1956, pp. 42-48 and 62-65. Poulsen, E.: Renal clearance in the cow. Royal Veterinary and Agri- cultural College, Yearbook, Copenhagen 1957, pp. 97-126. Schales, 0. & S. S. Schales: A simple and accurate method for the determination of chloride in biological fluids. J. biol. Chem. 1941, 140, 879-884. Smith, H. W.: The kidney. New York 1951, p. 159. Smith, H. W.: Principles of renal physiology. New York 1956, pp. 32, 102 and 104. Vogel, G.: Vergleichende Untersuchungen zur Kalium-Exkretion der Nieren verschiedener Haussaugetiere. Pfli.ig. Arch. ges. Physiol. 1959a, 269, 339-343. Vogel, G.: Zur Bestimmung von glomerularer Filtrationsrate und fil- trierender Flache in der Niere einiger Haussaugetiere. Pfli.ig. Arch. ges. Physiol. 1959b, 269, 264-269. Vogel, G.: Beitrage zur Kenntnis der Nierenphysiologie einiger Haus- siiugetiere. Beiheft 3, Zbl. Vet.-Med. 1962, p. 26.
SAMMENDRAG
Renale clearanceunders(Jgelser^ pd^ svin.^ Jnulin,^ endogen^ kreatinin, urinstof, para-aminohippursyre, natrium,^ kalium^ og klorid. Derer udf(Jrt renale clearanceunders0gelser^ pa^31 ikke^ anrestcse- redesvin med enlegemsvregtfra^28 ti1^ 123 kg.^ Undersjiigelserne^ omfat- tersimultan bestemmelseafclearance^ ved^ konstant^ plasmakoncentra- tion for^ inulin,^ endogen^ kreatinin,^ urinstof, para-aminohippursyre, natrium, kalium og klorid.Derfandtes^ fjiilgende^ vrerdier^ beregnetpr. 10 kg legemsvregt: lnulinclearance^21 ml/min., endogen^ kreatinin- clearance 22 ml/min.,urinstof-maksimal-clearance 12ml/min.,^ para- aminohippursyreclearance^64 ml/min. og^ clearance^ for^ natrium,^ ka- liumogkloridhenholdsvis^ 0,015,^ 2,8^ og^ 0,11^ ml/min. Deterdesuden vist,atinulin^ hos^ svineret filtrationsstof,idet clearanceeruafhrengig af diuresevariationer^ fra^ 0,07-1,91^ ml/min./ 10 kg ogaf variationeri^ inulinkoncentrationen^ i^ plasmafra^40 til^1900 μg/ml. Forholdetmellem inulinclearance^ og^ clearance^ forendogen^ krea- tinin vari gennemsnit 1,0^ varierende^ fra^ 0,8^ til^ 1,2.^ Filtrationsfrak- tionen (Crn/CpAff)^ blev bestemt^ til^ 0,33,^ ogden^ maximale^ tubulrere ekskretion af^ PAH^ var^23 mg/min./10^ kg.^ Ekstraktionsprocenten^ for PAH,^ derbestemtes^ pa^ anresteserede svin, blev^ fundet^ ti1^87 %.^ Det totale renale blood flower beregnet^ ti1^133 ml/min./10^ kg^ lgv. eller 363 ml/min./100^ g nyre.
(Received March^ 7,^ 1968).
