Estimation of the vascular resistance amplifier in the renal vascular bed in conscious hypertensive rabbits: comparison with the total peripheral vasculature

Figures

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  Figure 1. A. Resting renal vascular resistance (RVR; triangles) under conditions of effectors intact (EI), ganglionic block (GB) or neurohumoral block (NHB) in normotensive (N, solid symbols and lines) and hypertensive (H, open symbols and dashed lines) rabbits. For comparison, total peripheral resistance (TPR, circles; right y axis) data have been reproduced from Korner et al. [25]. Values are mean ± SEM (error bars not shown are contained within the symbol) from 7-9 rabbits under each condition. B. Ratios of hypertensive rabbit to normotensive rabbit (H:N) resting renal vascular resistance (RVR, triangles) and total peripheral resistance (TPR, circles) under the 3 conditions.

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  Figure 2. Noradrenaline i.a. infusion (μg/kg/min) dose-haemodynamic response curves in normotensive (n = 8–9; solid symbols and lines) and hypertensive (n = 7; open symbols and dashed lines) rabbits under three treatments (completed on separate experimental days): effectors intact (squares); ganglion block (triangles); and neurohumoral block (circles). 0, Baseline just before infusion of noradrenaline. Error bars are average SEM from repeated measures ANOVA (see Methods). Haemodynamic variables shown are: A. mean arterial pressure, MAP; B. heart rate; C. renal blood flow, Q; D. renal vascular conductance (renal Q/MAP), RVC; and E. renal vascular resistance (MAP/renal Q), RVR.

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  Figure 3. Angiotensin II i.a. infusion (μg/kg/min) dose-haemodynamic response curves in normotensive (n = 8–9; solid symbols and lines) and hypertensive (n = 7; open symbols and dashed lines) rabbits under three treatments (completed on separate experimental days): effectors intact (squares); ganglion block (triangles); and neurohumoral block (circles). 0, Baseline just before infusion of angiotensin II. Error bars are average SEM from repeated measures ANOVA (see Methods). Haemodynamic variables shown are: A. mean arterial pressure, MAP; B. heart rate; C. renal blood flow, Q; D. renal vascular conductance (renal Q/MAP), RVC; and E. renal vascular resistance (MAP/renal Q), RVR.

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  Figure 4. Acetylcholine i.a. infusion (μg/kg/min) dose-haemodynamic response curves in normotensive (n = 8–9; solid symbols and lines) and hypertensive (n = 7; open symbols and dashed lines) rabbits under three treatments (completed on separate experimental days): effectors intact (squares); ganglion block (triangles); and neurohumoral block (circles). 0, Baseline just before infusion of acetylcholine. Error bars are average SEM from repeated measures ANOVA (see Methods). Haemodynamic variables shown are: A. mean arterial pressure, MAP; B. heart rate; C. renal blood flow, Q; D. renal vascular conductance (renal Q/MAP), RVC; and E. renal vascular resistance (MAP/renal Q), RVR.

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  Figure 5. Adenosine i.a. infusion (μg/kg/min) dose-haemodynamic response curves in normotensive (n = 8–9; solid symbols and lines) and hypertensive (n = 7; open symbols and dashed lines) rabbits under three treatments (completed on separate experimental days): effectors intact (squares); ganglion block (triangles); and neurohumoral block (circles). 0, Baseline just before infusion of adenosine. Error bars are average SEM from repeated measures ANOVA (see Methods). Haemodynamic variables shown are: A. mean arterial pressure, MAP; B. heart rate; C. renal blood flow, Q; D. renal vascular conductance (renal Q/MAP), RVC; and E. renal vascular resistance (MAP/renal Q), RVR.

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  Figure 6. Average mean arterial pressure (MAP, mmHg; panel A) and average heart rate (beats/min; panel B) at rest (0 scaled dose), following i.a. infusions of acetylcholine (ACh, downward triangles) or adenosine (Aden, squares) at scaled doses -1 to -4 and following i.a. infusions of noradrenaline (NA, upward triangles) or angiotensin II (AngII, circles) at scaled doses +1 to +5. The data from the normotensive rabbits (Normo, n = 9) are shown by the solid symbols (solid lines) and from the hypertensive rabbits (Hyper, n = 7) in corresponding open symbols (dashed lines). For each agonist, 0 to -4 or 0 to +5, a 3rd order polynomial was fitted as shown by the respective lines. All measurements are from rabbits given neurohumoral block.

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  Figure 7. Combination graphs of effects of vasodilator and vasoconstrictor drug infusions on: A. renal vascular conductance (RVC); and B. renal vascular resistance (RVR). Each point is the mean of 7–9 rabbits infused i.a. with acetylcholine or adenosine at scaled doses -1 to -4 and noradrenaline or angiotensin II at scaled doses +1 to +5. The data from the normotensive rabbits (n = 8–9) are shown by the solid circles (solid lines) and from the hypertensive rabbits (n = 7) in corresponding open circles (dashed lines). In panel B, the insert graph shows data from scaled dose -4 to +2 on an enlarged y axis scale. For each rabbit group, -4 to +5, a 3rd order polynomial was fitted as shown by the respective lines. All measurements are from rabbits given neurohumoral block.

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  Figure 8. Combination graphs in rabbits with neurohumoral block showing (A) the hypertensive to normotensive ratio of renal vascular resistance, RVR, and (B) the renal average internal radius ri in normotensive rabbits (solid circles and lines; n = 8–9) and hypertensive rabbits (open circles and dashed lines; n = 7) over the range of vasodilator and vasoconstrictor stimuli. Vasodilator agonists acetylcholine or adenosine were infused (i.a.) at scaled doses -1 to -4 and vasoconstrictor agonists noradrenaline or angiotensin II infused at scaled doses +1 to +5. The lines are 3rd order polynomial fits.