Natural Killer T-Cells: A specialized subset of T-LYMPHOCYTES that exhibit features of INNATE IMMUNITY similar to that of NATURAL KILLER CELLS. They are reactive to glycolipids presented in the context of the major histocompatibility complex (MHC) class I-like molecule, CD1D ANTIGEN.Penis: The external reproductive organ of males. It is composed of a mass of erectile tissue enclosed in three cylindrical fibrous compartments. Two of the three compartments, the corpus cavernosa, are placed side-by-side along the upper part of the organ. The third compartment below, the corpus spongiosum, houses the urethra.Priapism: A prolonged painful erection that may lasts hours and is not associated with sexual activity. It is seen in patients with SICKLE CELL ANEMIA, advanced malignancy, spinal trauma; and certain drug treatments.Encephalitozoon: A genus of FUNGI originally considered a member of the class SPOROZOEA but now recognized as part of the class MICROSPOREA.Impotence, Vasculogenic: Inability to achieve and maintain an erection (ERECTILE DYSFUNCTION) due to defects in the arterial blood flow to the PENIS, defect in venous occlusive function allowing blood drainage (leakage) from the erectile tissue (corpus cavernosum penis), or both.Yawning: An involuntary deep INHALATION with the MOUTH open, often accompanied by the act of stretching.Phosphodiesterase 5 Inhibitors: Compounds that specifically inhibit PHOSPHODIESTERASE 5.Nepeta: A genus of the LAMIACEAE family. It is known for its mild calming effect and for the way cats are attracted to the aroma.SulfonesAnnexin A6: Protein of the annexin family with a probable role in exocytotic and endocytotic membrane events.Purines: A series of heterocyclic compounds that are variously substituted in nature and are known also as purine bases. They include ADENINE and GUANINE, constituents of nucleic acids, as well as many alkaloids such as CAFFEINE and THEOPHYLLINE. Uric acid is the metabolic end product of purine metabolism.Ejaculation: The emission of SEMEN to the exterior, resulting from the contraction of muscles surrounding the male internal urogenital ducts.PiperazinesAlprostadil: A potent vasodilator agent that increases peripheral blood flow.Moraxellaceae Infections: Infections with bacteria of the family MORAXELLACEAE.Nitric Oxide Synthase Type I: A CALCIUM-dependent, constitutively-expressed form of nitric oxide synthase found primarily in NERVE TISSUE.Copulation: Sexual union of a male and a female in non-human species.Sulpiride: A dopamine D2-receptor antagonist. It has been used therapeutically as an antidepressant, antipsychotic, and as a digestive aid. (From Merck Index, 11th ed)Phosphodiesterase Inhibitors: Compounds which inhibit or antagonize the biosynthesis or actions of phosphodiesterases.Cyclic Nucleotide Phosphodiesterases, Type 5: A cyclic nucleotide phosphodiesterase subfamily that is highly specific for CYCLIC GMP. It is found predominantly in vascular tissue and plays an important role in regulating VASCULAR SMOOTH MUSCLE contraction.Glanders: A contagious disease of horses that can be transmitted to humans. It is caused by BURKHOLDERIA MALLEI and characterized by ulceration of the respiratory mucosa and an eruption of nodules on the skin.Penile Induration: A condition characterized by hardening of the PENIS due to the formation of fibrous plaques on the dorsolateral aspect of the PENIS, usually involving the membrane (tunica albuginea) surrounding the erectile tissue (corpus cavernosum penis). This may eventually cause a painful deformity of the shaft or constriction of the urethra, or both.Choroid Hemorrhage: Hemorrhage from the vessels of the choroid.Orgasm: The climax of sexual excitement in either humans or animals.Libido: The psychic drive or energy associated with sexual instinct in the broad sense (pleasure and love-object seeking). It may also connote the psychic energy associated with instincts in general that motivate behavior.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Nitroso CompoundsPrajmaline: A derivative of the rauwolfia alkaloid AJMALINE. It is an anti-arrhythmia agent, but may cause liver damage.Muscle, Smooth: Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)Glasgow Outcome Scale: A scale that assesses the outcome of serious craniocerebral injuries, based on the level of regained social functioning.Nephrosclerosis: Hardening of the KIDNEY due to infiltration by fibrous connective tissue (FIBROSIS), usually caused by renovascular diseases or chronic HYPERTENSION. Nephrosclerosis leads to renal ISCHEMIA.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Periodontal Pocket: An abnormal extension of a gingival sulcus accompanied by the apical migration of the epithelial attachment and bone resorption.