Many commonly used antihypertensive drugs such as diuretics and beta-blockers can interfere with sexual function in both sexes, causing loss of libido, impairment of erectile function and ejaculation in men, and delay or prevent orgasm in women. Newly developed antihypertensive drugs should ideally not interfere with the patients’ quality of life including sexual function. This study examined the effects of losartan, a nonpeptide, specific antagonist for type I angiotensin II receptors, on the male sexual behavior of rats. Spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats were treated with losartan 30 mg/ kg/day or saline control for 7, 30 and 90 days. Dark-cycle video recording was used to analyze the male sexual activities of the rats. No significant alteration in male sexual performance was observed after 7 and 30 days of treatment with losartan. In contrast, SHRs treated with propranolol 5 mg/kg/day showed increases in intromission latency, ejaculation latency and postejaculatory period indicating decreased libido and erectile and ejaculatory function. Upon completion of 90 days of losartan administration, the mount latency of the SHR was significantly increased, suggesting a decrease in libido although other parameters were unchanged and there was no effect in WKY rats. It is therefore concluded that losartan may have an advantage in preservation of sexual function when used clinically for the treatment of hypertensive disorders.

We investigated the effects of chain architecture and hydrogen-bonding interaction on the phase behavior of binary mixtures containing nearly symmetric polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer and highly asymmetric polystyrenegraf t-poly(acrylic acid) (PS-g-PAA) graft copolymer. When PS-g-PAA was added to PS-b-P2VP, hydrogen bonds between PAA and P2VP chains improved the miscibility of the copolymers and facilitated localization of PS-g-PAA at the PS-b-P2VP interface, which reduced the interfacial free energy of the blends. However, positioning PS-g-PAA with one PS main chain and two PAA grafted chains at the PS-b-P2VP interface increased the stretching free energy of PS-b-P2VP. Consequently, the interfacial coverage of PS-g-PAA reached saturation. Residual PS-g-PAA was segregated into the PS microdomains formed by PS-b-P2VP to regain translational entropy and reduce the stretching free energy. When the molecular weight ratio of PS-b-P2VP to PS-g-PAA (R) was smaller than 8, PS-g-PAA could not swell the PS microdomains formed by PS-b-P2VP. Therefore, the morphology of PS-b-P2VP/PS-g-PAA blends remained lamellar. By contrast, when R > 8, PS-g-PAA effectively swelled the PS microdomains formed by PS-b-P2VP. This behavior amplified the asymmetry effect caused by the branched-chain architecture of PS-g-PAA on altering the interfacial curvature of PS-b-P2VP. Consequently, the morphology of the blends transformed into a cylindrical structure.