renal control of blood pressure and erythropoiesis SDL

Question 1

what is blood pressure

Answer 1

the product of cardiac output, which in turn is the product of stroke volume and heart rate, and systemic vascular resistance
BP=HRxSVxSVR

Question 2

blood pressure regulation involves

Answer 2

• CNS
• kidneys
• adrenal glands

each regulates cardiac output, fluid volume and peripheral vascular resistance

Question 3

what is one of the key pathways in regulation of blood presusre

Answer 3

sodium excretion by the kidneys and thus its effect on body fluid volume

Question 4

what controls sodium excretion and body fluid volume

Answer 4

RAAS

Question 5

what is pressure natriuresis

Answer 5

important in controlling circulating volume:
if perfusion to the kidneys is increased more fluid will be pushed through the kidney and the effect is to excrete more sodium and water to lo lower the circulating volume

Question 6

What is the normal blood pressure range in dogs and cats? How is it routinely measured?

Answer 6

Dogs:
systolic: 90-140 mm Hg
diastolic: 50-80 mm Hg
mean: 60-100 mmHg

cats:
syst: 80-140 mm Hg
diastolic: 55-75 mmHg
mean: 60-100 mmHg

Question 7

What are the main classifications of hypertension in cats?

Answer 7

• idiopathic (primary) where there is no apparent underlying disease
• secondary (thought to be due to underlying diseases or the use of therapeutic drugs

Question 8

One of the risks of hypertension (high blood pressure) is Target Organ Damage (TOD). What is TOD and which organs are most commonly affected by it?

Answer 8

damage that results from presence of sustained high BP
commonly effecting the eye, kidney, brain heart and blood vessels

Question 9

What are the general treatment guidelines for hypertension?

Answer 9

Because hypertension in dogs and cats often is secondary (≥80% of cases), antihypertensive drug treatment should be initiated along with treatment for any underlying or associated condition
- the goal of antihypertensive treatment is to decrease the likelihood of TOD

Question 10

List some of the drug groups that might be effective to manage hypertension medically

Answer 10

• ACE inhibitors = benazepril/enalapril
• angiotensin receptor blocker = telmisartan
• calcium channel blocker = amlodipine
• alpha 1 blocker = prazosin, phenoxybenzamine, acepromazine
• direct vasodilators = hydralazine
• aldosterone antagonsit = spironolactone
• beta blocker = propanolol, atenolol
• thiazide diuretic = hydrochlorothiazide
• loop diuretic = furosemide

Question 11

Where is erythropoietin produced and how does it work?

Answer 11

• produced predominantly by specialised cells called interstitial cells in the kidney
• acts on red bloods cells to protect them against destruction and stimulates stem cells of the bone marrow to increase production of RBCs

Question 12

What are the implications of having low EPO and when might we typically see this problem?

Answer 12

• low levels of EPO can lead to anemia
• typically seen in kidney disease