Hemodynamics of Early Experimental Renal Hypertension in Dogs

Overbeck, Henry W.

doi:10.1161/01.res.31.5.653

Cited by 64 publications

(17 citation statements)

References 26 publications

(31 reference statements)

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“…1,[13][14][15][16] Decreases in both unstressed vascular volume and compliance have been recorded in these models. 13,14,16,17 Venous compliance is also reduced in perinephritic hypertension in dogs 18 and in essential hypertension in humans. 19,20 In both animal and human hypertension, the decreases in venous capacitance occurred preferentially in the systemic veins and favored an increase in cardiopulmonary volume and CO. 14,21 Thus, there is convincing evidence that venous tone is increased in various models of hypertension.…”

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confidence: 99%

Venous Tone in the Developmental Stages of Spontaneous Hypertension

1998

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Abstract-The initial stages of hypertension in the spontaneously hypertensive rat (SHR) are characterized by an increase in cardiac output. Venous capacitance plays an important role in the control of cardiac output. This study tested the hypothesis that venous tone is elevated in the developmental stages of spontaneous hypertension. Male SHR or normotensive Wistar-Kyoto (WKY) rats were instrumented for the measurement of arterial pressure (FAP) and intrathoracic vena caval pressure (FVP). A latex-tipped catheter was advanced into the right atrium via the jugular vein. Mean circulatory filling pressure (MCFP), an index of integrated venomotor tone, was calculated as MCFPϭFVPϩ(FAPϪFVP)/VAR. FAP and FVP were recorded after 5 seconds of right atrial balloon inflation. The venous to arterial compliance ratio (VAR) was estimated as 76 for WKY and 106 for SHR. Mean arterial pressure (MAP), heart rate, and MCFP were recorded in conscious rats of 4 to 6 and 8 to 10 weeks of age. In 4-to 6-week-old rats, both MAP and MCFP were significantly elevated in the SHR (MAP, 129Ϯ6 mm Hg; MCFP, 6.6Ϯ0.4 mm Hg) compared with the age-matched WKY (MAP, 91Ϯ6 mm Hg; MCFP, 5.4Ϯ0.4 mm Hg), whereas heart rate was not significantly different. The elevations in MAP (SHR, 144Ϯ4 mm Hg; WKY, 102Ϯ3 mm Hg) and MCFP (SHR, 7.7Ϯ0.3 mm Hg; WKY, 6.0Ϯ0.2 mm Hg) in SHR were exaggerated at 8 to 10 weeks of age. After ganglionic blockade (chlorisondamine; 10 mg/kg), the differences in MCFP were no longer statistically significant between SHR and WKY at both 4 to 6 weeks of age (3.9Ϯ0.2 versus 4.0Ϯ0.3 mm Hg) and 8 to 10 weeks of age (5.0Ϯ0.3 versus 4.3Ϯ0.3 mm Hg, respectively). The differences in MAP at 4 to 6 weeks of age (79Ϯ7 versus 67Ϯ5 mm Hg, respectively) also were not statistically significant after ganglionic blockade. However, a significant difference in MAP between strains remained after ganglionic blockade in 8-to 10-week-old rats (90Ϯ5 versus 63Ϯ3 mm Hg, respectively). These findings indicate that venous tone is increased via autonomic effector systems during the developmental stages of spontaneous hypertension. These data also suggest that autonomic mechanisms predominate at very early stages, whereas nonautonomic mechanisms assume more importance in maintaining the elevated MAP as hypertension progresses. (Hypertension. 1998;31[part 1]:139-144.)

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confidence: 99%

Venous Tone in the Developmental Stages of Spontaneous Hypertension

1998

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“…It has been reported that venous compliance is decreased and venous contractility is enhanced in human essential hypertension (10)(11)(12) and also in experimental hypertensive animals (13)(14)(15)(16).…”

Section: Resultsmentioning

confidence: 99%

Venodilating Action of Nipradilol (K-351) in the Pithed Rat Pretreated with Dihydroergotamine

Shirasawa

Fujii

Nakamura

1985

Japanese Journal of Pharmacology

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Abstract-The venodilating action of nipradilol was investigated by monitoring arterial blood pressure (BP), cardiac output (CO), heart rate (HR) and central venous pressure (CVP) in pithed rats treated with dihydroergotamine (DHE) . DHE increased CVP and produced a simultaneous rise in BP and CO without ap preciable changes in total peripheral resistance (TPR) and HR, indicating that DHE reduces venous capacity through venoconstriction.Nipradilol caused a fall in CVP, BP and CO without changing the TPR in the DHE-pretreated rat. By com parison, hydralazine reduced BP and TPR without changes in CO. Propranolol produced only a transient decrease in BP and TPR. These results indicate that nipradilol dilates venous capacitance vessels and thereby decreases cardiac filling pressure in animals with high venous tone, whereas hydralazine preferentially dilates resistance vessels.

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“…Pre-and postcapillary resistances were determined by the isogravimetric method originally developed by Pappenheimer and SotoRivera. 1 ' Whole blood collected from a normotensive donor dog was used to perfuse all hindlimbs to minimize possible differences in blood chemistry between the groups. Briefly, several isogravimetric states were obtained for each hindlimb by reducing arterial pressure and increasing venous pressure to maintain hindlimb weight constant.…”

Section: Isogravimetric Experimentsmentioning

confidence: 99%

“…Likewise, Walsh et al ' found that hypertensive patients failed to demonstrate a decrease in venous distensibility after tilting, a phenomenon that occurred in normotensive patients. In experimental hypertension, venous responsiveness to norepinephrine 1 and adrenergic nerve stimulation" are enhanced.…”

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Pre- and postcapillary vascular responses to sympathetic nerve stimulation in DOCA-hypertensive dogs.

Brock¹,

Fleming²,

Diana³

1981

Hypertension

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SUMMARY Measurements of precapillary resistance (R.), postcapillary resistance (R v ), and mean capillary hydrostatic pressure (P c i) were made during sympathetic nerve stimulation (SNS) under constantflow perfusion in isolated hindlimbs from deoxycorticosterooe acetate (DOCA)-hypertensiTe dogs. We found that both pre-and postcapillary vascular responses to SNS were greater in the DOCA-hypertensive group when compared to the control group. Intraarterial injections of norepinephrine produced a dose-response curve for precapillary vessels in the hypertensive group that was asymmetrically shifted to the left (increased slope) and exhibited a significant decrease in vasoconstrictor threshold. These results, coupled with our earlier observations, suggest that the hyperresponslveness of the precapillary segment in DOCA-hypertensive dogs could be attributed to both structural and intrinsic alterations of the resistance vessels. We present evidence that suggests, however, that the increased postcapillary resistance with SNS may be explained by a structural alteration causing a decrease in the diameter of existing postcapillary vessels, or may be due to a decrease in the actual number of postcapillary vessels, or both. It is concluded that in this model of hypertension, postcapillary vascular changes also contribute to the overall increase in total peripheral resistance. The factors that contribute to this phenomenon remain unclear. In isolated hindlimbs from deoxycorticosterone acetate (DOCA)-hypertensive dogs, we previously demonstrated that the decreased venous distensibility was in part due to some form of structural alteration of the postcapillary segment. 10Hindlimbs from hypertensive dogs exhibited an increased venous resistance following maximal pharmacological vasodilation, as compared to control hindlimbs. The observed structural differences may be due to vascular hypertrophy, 11 an increase in vascular tissue water and electrolyte content ("waterlogging"), 13 ' » or both. There is additional evidence that the decreased venous distensibility in hypertension may also be due to increased venomotor tone. Takeshita and Mark* reported that venous distensibility increased significantly (20%) in patients with borderline hypertension following phentolamine infusion, but did not increase in normotensive patients. Likewise, Walsh et al.' found that hypertensive patients failed to demonstrate a decrease in venous distensibility after tilting, a phenomenon that occurred in normotensive patients. In experimental hypertension, venous responsiveness to norepinephrine 1 and adrenergic nerve stimulation" are enhanced.The present experiments were designed to study pre-and postcapillary vascular responses to sympathetic nerve stimulation (SNS) in deoxycorticosterone acetate (DOCA)-salt-induced hypertension. Our results demonstrate that the increased responses of the postcapillary vascular bed in the isolated hindlimbs from dogs with DOCA-salt hypertension may be due to one or more structural factors: 1) a decrease in the initi...

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Hemodynamics of Early Experimental Renal Hypertension in Dogs

Cited by 64 publications

References 26 publications

Venous Tone in the Developmental Stages of Spontaneous Hypertension

Venous Tone in the Developmental Stages of Spontaneous Hypertension

Venodilating Action of Nipradilol (K-351) in the Pithed Rat Pretreated with Dihydroergotamine

Pre- and postcapillary vascular responses to sympathetic nerve stimulation in DOCA-hypertensive dogs.

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