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The influence of increased renal mass on cardiovascular function in immature dogs
Insights
Increased renal mass in pediatric kidney transplant recipients does not appear to cause hypertension. This study in dogs suggests other factors may be involved in post-transplant hypertension and cardiovascular issues.
Area of Science:
- Nephrology
- Transplantation Immunology
- Pediatric Cardiology
Background:
- Pediatric renal allograft recipients often experience greater renal mass increases due to adult donors.
- These recipients have a higher incidence of post-transplant hypertension and cardiovascular complications.
- Pre-existing conditions and corticosteroid use are confounding factors in human studies.
Purpose of the Study:
- To investigate whether a significant increase in renal mass alone causes hypertension in immature recipients.
- To isolate the effect of increased renal mass on cardiovascular and renal function.
- To provide insights into the etiology of hypertension in pediatric kidney transplant patients.
Main Methods:
- Immature dogs underwent transplantation with adult donor kidneys, increasing renal mass by up to 50%.
- Cardiovascular and renal function were monitored before and after transplantation.
- Blood pressure, glomerular filtration rate, cardiac output, and plasma volume were assessed in anesthetized and conscious canine models.
Main Results:
- Blood pressure decreased significantly in both anesthetized and conscious canine recipients post-transplantation.
- Glomerular filtration rate showed transient decreases but normalized by 14 days.
- Cardiac output and plasma volume changes were variable but did not indicate sustained hypertension.
Conclusions:
- A renal mass increase of up to 50% does not induce hypertension in canine models.
- The findings suggest that factors other than increased renal mass contribute to hypertension in pediatric allograft recipients.
- Further research is needed to identify the specific factors implicated in post-transplant hypertension.
Abstract:
Pediatric renal allograft recipients receive a relatively greater increase in renal mass than do adult recipients because the donors are usually adults. They also have a higher frequency of posttransplant hypertension and cardiovascular problems. Avoiding other variables common to both pediatric and adult patients including pre-existing hypertension and renal disease and the use of corticosteroids, renal mass was increased by up to 50% in immature dogs by implanting large kidneys from adult dogs. Cardiovascular and renal function were studied before and after transplantation. Blood pressure was decreased in anesthetized mongrel pups at 2 hr and 3 days after surgery by 22 and 6 mm Hg, respectively; pressure was similarly reduced in conscious, chronically catheterized DLA-matched beagle pups maintained for 14 days, from 96.1 +/- 3.0 to 76.8 +/- 6.7 mm Hg (P less than 0.001). Glomerular filtration rate was decreased at 2 hr and 3 days, but was normal at 14 days. Cardiac output was reduced in four of five recipients at 2 hr but was unchanged at 3 days. Plasma volume was increased at 3 days in the mongrel dogs but was normal in the beagles both at 2 and 14 days. We conclude that an increase in renal mass of up to 50% by itself does not cause hypertension in the dog and that other factors may be implicated in pediatric allograft recipients.