Models of Hypertension

There are numerous hypertensive rodent models, and the cremaster muscle has been used to determine the effects of

Table II Normal Microvessel Diameters and Pressures.

Animal

Systemic blood pressure

Vessel

Resting diameter mm

Max diameter

Microvascular pressure

Reference

Rat

91 t 4

1st order

119 ± 7

46 t a

Meininger et al. 1984 [8]

2nd order

86 ± 5

4a t 2

3rd order

31 ± 3

t a

3rd order vein

53 ± 7

11 11

2nd order vein

141 ± 15

10 t1

1st order vein

218 ± 7

8 t 1

Mouse

10-80 mmHg

1st order

52 ± 3

61 t a

+

Hungerford et al. 2000 [9]

2nd order

18 ±2

40 t 2

3rd order

8 ±1

2a t 2

Hamster

+

1st order

+

+

+

2nd order

35 ± 6

51 t a*

Hester and Duling 1988 [10]

3rd order

22 ± 2

t a*

* arteriolar diameter response to tetanic stimulation. + not measured.

* arteriolar diameter response to tetanic stimulation. + not measured.

Table III Normal Microvessel Red Cell Velocity and Blood Flow.

Animal Vessel Tissue blood flow Vessel Red cell Blood flow Reference ml/min/100gm diameter mm velocity mm/sec nl/sec

Animal Vessel Tissue blood flow Vessel Red cell Blood flow Reference ml/min/100gm diameter mm velocity mm/sec nl/sec

Rat

Arteriole 43

40 t 4

9.0 t 1.5

S.7 t 2.0

Proctor and Busija 19S5 [6]

Hamster

Arteriole

44 t 6

6.9 t 2

11 t 7

Hester and Duling 19SS [10]

8

30 t 3

5.1 t 0.S

5 t 2

Klitzman and Duling 1979 [7]

Rat

Capillary

5.1 t 0.1

100 mm/sec

Klitzman and Duling 1979 [7]

Table IV

Cardiovascular and Microvessel Parameters in Hypertension Models.

Animal

Condition

Systemic

Vessel

Diameter mm

Microvascular

Reference

blood pressure

pressure mmHg

Rat

1 kidney

164 t 11

1st order

77 t 5

60 t 5

Meininger et al. 19S4 [S]

1 clip hypertension

2nd order

53 t 4

50 t 6

3rd order

26 t 3

39 t 3

Rat

2 kidney

130 t S

1st order

92 t 10

53 t 6

Meininger et al. 19S4 [S]

1 clip hypertension

2nd order

5S t 6

41 t 5

3rd order

24 t 3

34 t 4

Rat

DOCA-salt

134 t 17

1st order

67 t 7

62 t 12

Meininger et al. 19S4 [S]

hypertension

2nd order

4S t 6

55 t 5

3rd order

1S t 3

47 t 3

Rat

SHR hypertension

11S t 12

1st order

SS t 4

Falcone et al. 1993 [11]

3rd order

26 t 2

hypertension on the microcirculation. Table IV provides data for baseline arterial pressures, diameters, and microvascular pressures in four models of hypertension. Venular data is not presented because the values are similar to normal values (Table I).

Advantages

As a result of the ease of preparation, the cremaster muscle preparation has been used extensively to study the microcirculation. The total time for preparation of the muscle is approximately one hour. With suitable surgical training, it is easy to have preparations that have substantial vascular tone. The muscle will contract vigorously in response to field stimulation, resulting in an increase in oxygen consumption, blood flow, and arteriolar diameter.

Disadvantages

The cremaster is not a true postural muscle, and the arrangement of the muscle fibers is different from most postural muscles. The muscle fibers run oblique to each other, and even though there are discreet areas supplied by capillaries, this delineation is not readily observable. The outside areas of the cremaster should be avoided for study because these vessels are dilated as a result of the surgical procedure.

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