Figure 5.

Low‐dose propranolol causes systemic peripheral vasoconstriction. (A–D) Representative tracings of propranolol effects on arterial BP and HR. Intraperitoneal administration of 20 mg·kg⁻¹ of propranolol had no effect on BP whereas 40 mg·kg⁻¹ decreased it (A,B). Both doses of propranolol reduced HR (C,D). (E–G) Representative echocardiographic M‐mode images of the LV. Administration of 20 or 40 mg·kg⁻¹ of propranolol had minimal effects on fractional shortening (see Results section). (H) Propranolol effects on CO. Both doses of propranolol significantly reduced CO by about 20%. CO was calculated as the product of SV and HR; n = 5 per group. * P < 0.05, significantly different from the respective basal values. (I) Propranolol effects on SVR. SVR was increased by 20 mg·kg⁻¹ of propranolol, whereas it returned to basal values after administration of 40 mg·kg⁻¹. SVR was calculated as mean arterial pressure (MAP) divided by CO. n = 5 per group; * P < 0.05, significantly different from the respective basal values).