Sotalol, in particular, has additional antiarrhythmic properties and prolongs action potential duration through potassium channel blockade. Blockade of the sympathetic nervous system on renin release leads to reduced aldosterone via the renin–angiotensin–aldosterone system, with a resultant decrease in blood pressure due to decreased sodium and water retention. Intrinsic sympathomimetic activity
Also referred to as intrinsic sympathomimetic effect, this term is used particularly with beta blockers that can show both agonism and antagonism at a given beta receptor, depending on the concentration of the agent (beta blocker) and the concentration of the antagonized agent (usually an endogenous compound, such as norepinephrine). See partial agonist for a more general description. Some beta blockers (e.g. oxprenolol, pindolol, penbutolol, labetalol and acebutolol) exhibit intrinsic sympathomimetic activity (ISA). These agents are capable of exerting low-level agonist activity at the β-adrenergic receptor while simultaneously acting as a receptor site antagonist. These agents, therefore, may be useful in individuals exhibiting excessive bradycardia with sustained beta blocker therapy. Agents with ISA should not be used for patients with any kind of angina as it can aggravate or after myocardial infarctions. They may also be less effective than other beta blockers in the management of angina and tachyarrhythmia. α1-receptor antagonism
Some beta blockers (e.g., labetalol and carvedilol) exhibit mixed antagonism of both β- and α1-adrenergic receptors, which provides additional arteriolar vasodilating action. Examples
Nonselective agents
Nonselective beta blockers display both β1 and β2 antagonism.
In contrast, however, mouth breathing "pulls all pollution and germs directly into the lungs; dry cold air in the lungs makes the secretions thick, slows the cleaning cilia, and slows down the passage of oxygen into the bloodstream." As a result, chronic mouth breathing may lead to illness. In about 85% of cases, it is an adaptation to nasal congestion,: 281  and frequently occurs during sleep. More specialized causes include: antrochoanal polyps;: 350  a short upper lip which prevents the lips from meeting at rest (lip incompetence);: 281  and pregnancy rhinitis which tends to occur in the third trimester of pregnancy. : 435

Potential effects
Conditions associated with mouth breathing include cheilitis glandularis,: 490  Down syndrome,: 365  anterior open bite,: 225  tongue thrusting habit,: 225  cerebral palsy,: 422  ADHD, sleep apnea, and snoring. In addition, gingivitis,: 85  gingival enlargement,: 85  and increased levels of dental plaque: 108  are common in persons who chronically breathe through their mouths. The usual effect on the gums is sharply confined to the anterior maxillary region, especially the incisors (the upper teeth at the front). The appearance is erythematous (red), edematous (swollen) and shiny. This region receives the greatest exposure to airflow during mouth breathing, and it is thought that the inflammation and irritation is related to surface dehydration, but in animal experimentation, repeated air drying of the gums did not create such an appearance. : 85 Breathing through your mouth decreases saliva flow. Saliva has minerals to help neutralize bacteria, clean off the teeth, and rehydrate the tissues.