Figure 1.
Effect of Age and Rat Strain on Vasomotor Responses in Thoracic Aortic Rings.
Representative traces (A) were recorded in PE (1 µM)-induced contraction and the subsequent ACh (10 µM)-induced relaxation of aortic rings. Tensions in contraction (B) and relaxation (C) were measured for aortic rings taken from both 8- and 40-week WKY and SHR. The ratio of reduced tension by ACh to increased tension by PE was used for the vasomotor response index (D). Results are expressed as the mean ± SEM values (n = 4–8). *P<0.05, **P<0.01 vs 8-week SHR.
Figure 2.
Profiles of Ang II-Induced Contraction in Both WKY and SHR.
Representative traces (A) were recorded in Ang II (1 µM)-induced contraction of aortic rings. Tension in contraction by Ang II was measured in aortic rings from both 8- and 40-week WKY and SHR in the presence of PD123177 (1 µM, AT2R inhibitor) (B). Results are expressed as the mean ± SEM (n = 4–5). *P<0.05 vs 8-week SHR, ‡P<0.01 vs 40-week WKY.
Figure 3.
Protein Expressions of AT1R and AT2R in Aorta by Western Blot Analysis and Confocal Microscopy.
Representative blots are shown for AT1R (A) and AT2R (B). The amounts of AT1R and AT2R were determined as the ratio of either AT1R (C) or AT2R (D) to β-actin. Results are expressed as the mean ± SEM (n = 3–5). *P<0.05 vs each 8-week rat strain. The expression levels were determined by immunofluorescence staining. Confocal measurements of both AT1R (E) and AT2R (F) were performed on rat aortic segments (14 µm).
Figure 4.
Profiles of Bay K 8644-induced contraction in Both WKY and SHR.
Representative traces (A) were recorded in Bay K 8644 (1 µM)-induced contracted aortic rings. Tension in contraction by Bay K 8644 was measured in aortic rings from both 8- and 40-week WKY and SHR at initial (3 min after the addition) phase (B) and at plateau (20 min after the addition) phase (C). Results are expressed as the mean ± SEM (n = 3). *P<0.05, **P<0.01 vs each 8-week rat strain.
Figure 5.
Protein Expression of VDCC in Aorta by Both Western Blot Analysis and Confocal Microscopy.
Representative blots are shown for VDCC (A). The amount of the alpha-1c subunit of VDCC was determined as the ratio of VDCC to β-actin (B). Results are expressed as the mean ± SEM (n = 6). **P<0.01 vs each 8-week rat strain. Confocal measurement of VDCC (C) was performed in rat aortic segments (14 µm).
Figure 6.
Profiles of Relaxation by VDCC Blockers in Both WKY and SHR.
Representative traces of nifedipine (A)-, verapamil (C)-, and Trp-His (E)-induced relaxation in PE (1 µM)-contracted aortic rings from both 8- and 40-week WKY and SHR. The relaxation activity was represented as EC50 values for nifedipine (B), verapamil (D), and Trp-His (F). Results are expressed as the mean ± SEM values (n = 3–7). *P<0.05 vs each 8-week rat strain, †P<0.05 vs age-matched WKY.