scholarly journals Intrapericardial denervation: responses to water immersion in rhesus monkeys

1995 ◽  
Vol 268 (4) ◽  
pp. R1040-R1049 ◽  
Author(s):  
K. H. McKeever ◽  
L. C. Keil ◽  
H. Sandler
Keyword(s):  
Rhesus Monkeys ◽  
Diastolic Pressure ◽  
Water Immersion ◽  
Free Water ◽  
Plasma Renin ◽  
Fractional Excretion ◽  
Free Water Clearance ◽  
Cardiac Denervation ◽  
Gauge Pressure ◽  
Electromagnetic Flow Probe

Eleven anesthetized rhesus monkeys were used to study cardiovascular, renal, and endocrine alterations associated with 120 min of head-out water immersion. Five animals underwent complete intrapericardial denervation using the Randall technique, while the remaining six monkeys served as intact controls. Each animal was chronically instrumented with an electromagnetic flow probe on the ascending aorta, a strain gauge pressure transducer implanted in the apex of the left ventricle (LV), and electrocardiogram leads anchored to the chest wall and LV. During immersion, LV end-diastolic pressure, urine flow, glomerular filtration rate, sodium excretion, and circulating atrial natriuretic peptide (ANP) each increased (P < 0.05) for intact and denervated monkeys. There were no alterations in free water clearance in either group during immersion, yet fractional excretion of free water increased (P < 0.05) in the intact monkeys. Plasma renin activity (PRA) decreased (P < 0.05) during immersion in intact monkeys but not the denervated animals. Plasma vasopressin (PVP) concentration decreased (P < 0.05) during the first 30 min of immersion in both groups but was not distinguishable from control by 60 min of immersion in denervated monkeys. These data demonstrate that complete cardiac denervation does not block the rise in plasma ANP or prevent the natriuresis associated with head-out water immersion. The suppression of PVP during the first minutes of immersion after complete cardiac denervation suggests that extracardiac sensing mechanisms associated with the induced fluid shifts may be responsible for the findings.

Lithium clearance in water immersion-induced natriuresis in humans

1989 ◽  
Vol 66 (4) ◽  
pp. 1744-1748 ◽  
Author(s):  
T. J. Rabelink ◽  
H. A. Koomans ◽  
W. H. Boer ◽  
J. van Rijn ◽  
E. J. Dorhout Mees
Keyword(s):  
Healthy Subjects ◽  
Water Immersion ◽  
Free Water ◽  
Fractional Excretion ◽  
Lithium Clearance ◽  
Free Water Clearance ◽  
Time Control ◽  
Fractional Excretion Of Phosphate ◽  
Response To Water ◽  
Glomerulotubular Balance

Lithium clearance (CLi) has been advanced as a measure of sodium delivery from the proximal tubules. Because information on the intrarenal effects of water immersion is only limited, and available data are conflicting with respect to the effects on the proximal tubule, we examined the effects of 3 h of water immersion on renal functional parameters, including CLi, in eight healthy subjects. Studies were carried out during maximal water diuresis. Water immersion resulted in a significant increase in sodium excretion, from preimmersion values of 74.0 +/- 9.6 to 155.4 +/- 12.0 mumol/min at the third immersion hour (P less than 0.01). This natriuresis was accompanied by an increase in CLi from 26.3 +/- 1.9 (preimmersion) to 37.0 +/- 3.1 ml/min (P less than 0.01). Fractional lithium reabsorption (FRLi) decreased from 76.4 +/- 1.0 to 69.6 +/- 1.3% (P less than 0.01). None of these changes was found in eight healthy subjects undergoing a time-control study without water immersion. The large fall in FRLi found during immersion is compatible with a major resetting of the proximal glomerulotubular balance. In this regard the renal response to water immersion resembles saline expansion rather than mere intravascular expansion. The lithium data suggested a large rise in distal delivery accompanied by an almost as large rise in distal reabsorption. The free water clearance data were in agreement with this interpretation. However, no changes were found in fractional excretion of phosphate and uric acid. Therefore such a major resetting of proximal glomerulotubular balance can be doubted.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular, renal, and endocrine responses in male quadriplegics during head-out water immersion

1990 ◽  
Vol 258 (6) ◽  
pp. R1424-R1430 ◽  
Author(s):  
F. Tajima ◽  
S. Sagawa ◽  
J. Iwamoto ◽  
K. Miki ◽  
B. J. Freund ◽  
...  
Keyword(s):  
Water Immersion ◽  
Urine Volume ◽  
Systolic Pressure ◽  
Free Water ◽  
Plasma Renin ◽  
Normal Subjects ◽  
Urine Flow ◽  
Cervical Cord ◽  
Free Water Clearance ◽  
Normal Men

The present study was undertaken to determine the relative influence of the action of the central nervous system on the mechanism of water-immersion-induced diuresis by comparing physiological responses of quadriplegic (QP) and normal subjects. After overnight fasting seven male QP subjects with complete cervical cord transections (C5-C8) and six normal men were tested before, during, and after 3 h of head-out immersion (HOI) in thermoneutral water (34.5-35.0 degrees C). The reversible increase in urine flow and the total urine volume (309 +/- 53 ml in 3 h) in QP subjects were comparable with that of the normal subjects (318 +/- 96 ml in 3 h). While osmolal excretion was increased in QP subjects, its magnitude was less when compared with that of normal subjects. Instead, the increased urine flow in QP subjects was characterized by increased glomerular filtration rate (GFR) and free water clearance, in contrast to a predominantly osmotic diuresis with no changes in GFR in the normal subjects. The HOI elevated (P less than 0.05) systolic pressure only in QP subjects, whereas the increase in cardiac output was the same in both groups. While plasma renin activity and aldosterone responses to HOI in QP subjects were comparable with those of normal individuals, plasma atrial natriuretic factor (ANF) in QP subjects was twofold higher (P less than 0.05) during HOI, and the approximately threefold increase in ANF (P less than 0.05) in QP subjects due to HOI was the same as that of normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of the Natriuresis Caused in Normal Man by Immersion in Water

1972 ◽  
Vol 43 (2) ◽  
pp. 275-287 ◽  
Author(s):  
M. Epstein ◽  
D. C. Duncan ◽  
L. M. Fishman
Keyword(s):  
Water Immersion ◽  
Control Period ◽  
Free Water ◽  
Fractional Excretion ◽  
Normal Male ◽  
Free Water Clearance ◽  
Fractional Excretion Of Sodium ◽  
Sodium Load ◽  
Proximal Tubular ◽  
Normal Man

1. The effects of 4–6 h of water immersion on the renal excretion of water and electrolytes were studied in thirteen normal male subjects in balance on a constant diet containing 150 mEq of Na and 100 mEq of K per day. Each subject was studied during a control period, consisting of quiet sitting, and during water immersion to the neck. 2. Immersion resulted in a natriuresis beginning within the first hour, with the rate of sodium excretion eventually exceeding that of the control period by 3–4-fold; potassium excretion also increased. Despite a progressively negative water balance during the immersion studies, urine flow was greater during the first 4 h and free water clearance was greater during the first 2 h of immersion than during the control study. 3. The demonstration of a highly significant increase in fractional excretion of sodium during immersion suggests that the natriuresis of water immersion is not attributable to changes in filtered sodium load. 4. The prompt onset of the natriuresis, the concomitant kaliuresis and the fact that aldosterone secretion under the conditions of study was probably already suppressed make it unlikely that the natriuresis of water immersion is mediated solely by decreases in aldosterone activity. 5. The data suggest that the natriuresis caused by water immersion is the result of decreased fractional reabsorption of sodium proximal to the renal diluting site. The mechanism whereby increased proximal tubular sodium rejection occurs in relation to immersion remains unclear.

Role of cardiac nerves in response to head-out water immersion in conscious dogs

1987 ◽  
Vol 253 (2) ◽  
pp. R242-R253 ◽  
Author(s):  
G. Hajduczok ◽  
K. Miki ◽  
S. K. Hong ◽  
J. R. Claybaugh ◽  
J. A. Krasney
Keyword(s):  
Heart Rate ◽  
Time Course ◽  
Water Immersion ◽  
Peripheral Resistance ◽  
Free Water ◽  
Plasma Renin ◽  
Left Ventricular ◽  
Right Atrial ◽  
Free Water Clearance ◽  
Striking Change

The circulatory, renal, and hormonal responses during 100 min of thermoneutral (37 degrees C) head-out water immersion (WI) were investigated in conscious intact (INT) and cardiac-denervated (CD) dogs. In the INT group, both left and right atrial and aortic transmural distending pressures and left ventricular contractile performance (LV dP/dtmax) increased, and total peripheral resistance remained unchanged. Cardiac output (QCO) increased in association with an increase in heart rate and LV dP/dtmax. Urine flow (V), sodium excretion (UNaV), and osmolal clearance (Cosmol) all increased, whereas glomerular filtration rate, as indicated by creatinine clearance (CCr), remained constant. The diuresis and natriuresis occurred in the absence of any significant changes in plasma levels of antidiuretic hormone (ADH), aldosterone, or plasma renin activity. The CD animals showed a similar hemodynamic response except that the increase in QCO was now associated with an increase in stroke volume and no change in heart rate or LV dP/dtmax. Although the increase in V was similar in both magnitude and time course of the INT animals, there was no significant change in UNaV. Thus there is a striking change in the character of the response of the denervated group in that the natriuresis is abolished and, instead, a water diuresis occurred. Free water clearance increased, but no significant changes in Cosmol or CCr were observed. In addition plasma ADH levels significantly declined during WI in the CD group. These data indicate that cardiac receptors are important in determining the nature of the renal response to WI.

Estrogen effects on osmotic regulation of AVP and fluid balance

2002 ◽  
Vol 283 (4) ◽  
pp. E711-E721 ◽  
Author(s):  
Nina S. Stachenfeld ◽  
David L. Keefe
Keyword(s):  
Free Water ◽  
Plasma Renin ◽  
Fractional Excretion ◽  
Hormone Treatment ◽  
Osmotic Regulation ◽  
Gnrh Analog ◽  
Free Water Clearance ◽  
Fractional Excretion Of Sodium ◽  
Endogenous Estrogen ◽  
Estrogen Effects

To determine estrogen effects on osmotic regulation of arginine vasopressin (AVP) and body fluids, we suppressed endogenous estrogen and progesterone using the gonadotropin-releasing hormone (GnRH) analog leuprolide acetate (GnRHa). Subjects were assigned to one of two groups: 1) GnRHa alone, then GnRHa + estrogen (E, n = 9, 25 ± 1 yr); 2) GnRHa alone, then GnRHa + estrogen with progesterone (E/P, n = 6, 26 ± 3). During GnRHa alone and with hormone treatment, we compared AVP and body fluid regulatory responses to 3% NaCl infusion (HSI, 120 min, 0.1 ml · min−1 · kg body wt−1), drinking (30 min, 15 ml/kg body wt), and recovery (60 min of seated rest). Plasma [E2] increased from 23.9 to 275.3 pg/ml with hormone treatments. Plasma [P4] increased from 0.6 to 5.7 ng/ml during E/P and was unchanged (0.4 to 0.6 ng/ml) during E. Compared with GnRHa alone, E reduced osmotic AVP release threshold (275 ± 4 to 271 ± 4 mosmol/kg, P < 0.05), and E/P reduced the AVP increase in response during HSI (6.0 ± 1.3 to 4.2 ± 0.6 pg/ml at the end of HSI), but free water clearance was unaffected in either group. Relative to GnRHa, pre-HSI plasma renin activity (PRA) was greater during E (0.8 ± 0.1 vs. 1.2 ± 0.2 ng ANG I · ml−1 · h−1) but not after HSI or recovery. PRA was greater than GnRHa during E/P at baseline (1.1 ± 0.2 vs. 2.5 ± 0.6) and after HSI (0.6 ± 0.1 vs. 1.1 ± 1.1) and recovery (0.5 ± 0.1 vs. 1.3 ± 0.2 ng ANG I · ml−1 · h−1). Baseline fractional excretion of sodium was unaffected by E or E/P but was attenuated by the end of recovery for both E (3.3 ± 0.6 vs. 2.4 ± 0.4%) and E/P (2.8 ± 0.4 vs 1.7 ± 0.4%, GnRHa alone and with hormone treatment, respectively). Fluid retention increased with both hormone treatments. Renal sensitivity to AVP may be lower during E due to intrarenal effects on water and sodium excretion. E/P increased sodium retention and renin-angiotensin-aldosterone stimulation.

Volume-homeostatic mechanisms in humans during a 12-h posture change

1993 ◽  
Vol 75 (1) ◽  
pp. 349-356 ◽  
Author(s):  
P. Norsk ◽  
C. Stadeager ◽  
L. B. Johansen ◽  
J. Warberg ◽  
P. Bie ◽  
...  
Keyword(s):  
Sodium Excretion ◽  
Venous Pressure ◽  
Free Water ◽  
Plasma Renin ◽  
Arterial Pulse ◽  
Free Water Clearance ◽  
Water Handling ◽  
Renal Sodium Excretion ◽  
Male Subjects ◽  
Peak Value

On one day six male subjects underwent an upright seated (SEAT) study, and on another day they were subjected to a head-down tilt of 3 degrees (HDT). Compared with SEAT, HDT induced prompt increases in central venous pressure (CVP) from -0.5 +/- 0.8 to 8.3 +/- 0.3 mmHg (P < 0.001) and in arterial pulse pressure of 8–18 mmHg (P < 0.001). CVP stabilized after 6 h at levels 2.4–2.8 mmHg below the peak value. Simultaneously, renal sodium excretion gradually increased over the initial 5 h of HDT and stabilized at a level approximately 125 mumol/min over that of SEAT (P < 0.001). Urine flow rate and solute free water clearance increased during the initial 2–6 h of HDT (P < 0.001) but returned to the level of SEAT thereafter. We concluded that CVP is slightly reduced over 12 h of HDT and that a clear temporal dissociation exists between renal sodium and water handling. We suggest that the combined effect of the sustained suppressions of plasma renin activity and plasma aldosterone and norepinephrine concentrations constitutes a mechanism of the increase in renal sodium excretion.

Role of atrial natriuretic peptide and urinary cGMP in the natriuretic and diuretic response to central hypervolemia in normal human subjects

1987 ◽  
Vol 65 (10) ◽  
pp. 2076-2080 ◽  
Author(s):  
W. M. Leung ◽  
A. G. Logan ◽  
P. J. Campbell ◽  
T. E. Debowski ◽  
S. B. Bull ◽  
...  
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Water Immersion ◽  
Free Water ◽  
Base Line ◽  
Free Water Clearance ◽  
Diuretic Response ◽  
Line Level ◽  
Central Hypervolemia ◽  
Atrial Natriuretic

The response of plasma atrial natriuretic peptide (ANP) and urinary cGMP excretion to central hypervolemia induced by water immersion was assessed twice in five healthy male subjects, once while immersed in water to the neck for 3 h and again on a control day. Plasma ANP and urinary cGMP were measured by radioimmunoassay. Compared with the control day, overall change in plasma ANP on the immersion day was significant (p < 0.05). In response to water immersion, plasma ANP increased from a base-line level of 13.2 ± 3.1 (mean ± SEM) to 24.2 ± 5.5 pg/mL by 0.5 h of immersion and was sustained at that level throughout the immersion period. Plasma ANP returned to the base-line level at 1 h postimmersion. Urinary cGMP excretion increased significantly by 1 h of immersion and was sustained at that level throughout water immersion and 1 h postimmersion (p < 0.05). During water immersion urine flow, urinary sodium and potassium excretion, free water clearance, and osmolar clearance increased while plasma renin activity, serum aldosterone, and blood pressure fell; all changes were significant (p < 0.05). Creatinine clearance and hematocrit did not show any significant changes. These data suggest that an increase in plasma ANP may contribute to the natriuretic and diuretic response to central hypervolemia, and that the measurement of urinary cGMP may be a valuable marker of ANP biological responsiveness.

Role of ANP in natriuresis of head-out immersion in humans

1989 ◽  
Vol 257 (3) ◽  
pp. F375-F382 ◽  
Author(s):  
T. J. Rabelink ◽  
H. A. Koomans ◽  
P. Boer ◽  
C. A. Gaillard ◽  
E. J. Dorhout Mees
Keyword(s):  
Renal Plasma Flow ◽  
Water Immersion ◽  
Free Water ◽  
Urine Osmolality ◽  
Sodium Absorption ◽  
Free Water Clearance ◽  
Target Segment ◽  
Small Rise ◽  
Natriuretic Effect

Atrial natriuretic peptide (ANP) may play a role in the natriuresis after acute circulatory challenges. To assess this role in head-out water immersion (HOI), we compared in clearance studies the effect of 3 h HOI with an equally natriuretic 3-h infusion of ANP [0.01 microgram.kg-1.min-1 human ANP-(99-126)] in seven healthy individuals taking a 100 mmol sodium diet. The studies were repeated after treatment with enalapril (20 mg twice daily), which in previous studies inhibited the natriuresis after ANP. HOI caused a natriuresis equal to that of ANP infusion despite an about five times smaller rise in plasma ANP. HOI increased and ANP decreased estimated renal plasma flow (ERPF). HOI increased maximal free water clearance and decreased fractional lithium reabsorption. ANP did not affect these variables but raised minimal urine osmolality. Enalapril enhanced the fall in ERPF caused by ANP and abolished its natriuretic effect; enalapril did not impair either the natriuresis after HOI or the increase in ERPF and the fall in lithium reabsorption. These data indicate that the low dosage of ANP causes natriuresis by reducing sodium absorption in a distal nephron target segment; enalapril impairs this effect, perhaps by enhancing ANP-induced vasoconstriction, which decreases delivery to this target segment. HOI, by increasing sodium delivery to this segment, is natriuretic despite only a small rise in plasma ANP. Enalapril does not impair these effects. Although a rise in plasma ANP may be one factor in the natriuresis of HOI, the present data speak against an exclusive role. Other factors determine the magnitude of the natriuretic response.

Contribution of peripheral pooling to the renal response to immersion in the dog

1978 ◽  
Vol 45 (5) ◽  
pp. 786-790 ◽  
Author(s):  
I. H. Zucker ◽  
J. P. Gilmore
Keyword(s):  
Renal Plasma Flow ◽  
Water Immersion ◽  
Venous Pressure ◽  
Free Water ◽  
Urine Flow ◽  
Peripheral Vascular ◽  
Central Venous ◽  
Free Water Clearance ◽  
Hormone Administration ◽  
Cervical Vagotomy

The present investigation evaluated the renal and hemodynamic responses to head-out water immersion in dogs. Dogs were immersed in the vertical (seated) position in a 34 degrees C bath. Urine flow (V), osmolar clearance (Cosm), free water clearance (CH2O), sodium excretion (UNa+V), potassium excretion (UK+V), GFR, effective renal plasma flow (ERPF), central venous pressure (CVP), and cardiac output (CO) all increased significantly during immersion. This response was unchanged by bilateral cervical vagotomy or by deoxycorticosterone acetate and antidiuretic hormone administration. The control values of these dogs were low and indicated a state of peripheral vascular pooling which was readjusted to normal by the immersion maneuver. The renal and hemodynamic values during the period of immersion were similar to values of a group of dogs which were recumbent in air. Furthermore, when the latter group of dogs were tilted head down 19 degrees, there was no further increase in any of the measured parameters. These data are consistent with the view that water immersion in the upright dog simply redistributes blood volume back to that level seen in the recumbent dog, a position which is more natural for this species.

Nephron site of effect of nonsteroidal anti-inflammatory drugs on solute excretion in humans

1983 ◽  
Vol 244 (2) ◽  
pp. F134-F139 ◽  
Author(s):  
S. Kaojarern ◽  
P. Chennavasin ◽  
S. Anderson ◽  
D. C. Brater
Keyword(s):  
Free Water ◽  
Fractional Excretion ◽  
Thick Ascending Limb ◽  
Diluting Segment ◽  
Free Water Clearance ◽  
Water Loading ◽  
Fractional Excretion Of Sodium ◽  
Inflammatory Drugs ◽  
Anti Inflammatory ◽  
Solute Excretion

Indomethacin and other nonsteroidal anti-inflammatory drugs (NSAIDs) decrease solute excretion when administered acutely to normal subjects. We performed clearance studies during water loading of 10 normal volunteers and during hydropenia in eight additional subjects to determine the nephron site of this effect using indomethacin and carprofen as inhibitors of prostaglandin (PG) synthesis. Their administration decreased fractional excretion of sodium, chloride, and volume. During water loading, fractional clearance of free water decreased from 0.13 +/- 0.04 during the control study to 0.09 +/- 0.03 and 0.06 +/- 0.02 with indomethacin and carprofen, respectively. However, fractional delivery of solute to the dilution segment decreased in parallel such that free water clearance corrected for delivery did not change with either drug. In humans, therefore, the decrement in solute excretion that occurs with administration of NSAIDs occurs prior to the diluting segment. During hydropenia, free water reabsorption relative to osmolar clearance increased (P less than 0.01). In both studies, neither the marker of renal perfusion or of proximal nephron function changed with inhibition of PG synthesis. The data indicate that at the tubular level, NSAIDs increase solute reabsorption at the medullary segment of the thick ascending limb of the loop of Henle. Therefore, a physiologic role of renal prostaglandins at this nephron site is implied.

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